[escher] Change dynamic view controller paradigm

Change-Id: I57fd41c9b9ad8a1e8b684b97fdf80ddffd71881d

apps/apps_container.cpp

@@ -120,7 +120,9 @@ bool AppsContainer::dispatchEvent(Ion::Events::Event event) {
 }
 
 void AppsContainer::switchTo(App * app) {
-  m_window.setTitle(app->upperName());
+  if (app) {
+    m_window.setTitle(app->upperName());
+  }
   Container::switchTo(app);
 }
 

apps/calculation/edit_expression_controller.cpp

@@ -97,18 +97,17 @@ TextFieldDelegateApp * EditExpressionController::textFieldDelegateApp() {
   return (App *)app();
 }
 
-void EditExpressionController::loadView() {
-  m_historyController->loadView();
-  DynamicViewController::loadView();
-}
-
-void EditExpressionController::unloadView() {
-  m_historyController->unloadView();
-  DynamicViewController::unloadView();
-}
-
-View * EditExpressionController::createView() {
+View * EditExpressionController::loadView() {
   return new ContentView(this, (TableView *)m_historyController->view(), this);
 }
 
+void EditExpressionController::unloadView(View * view) {
+  delete view;
+}
+
+void EditExpressionController::viewDidDisappear() {
+  DynamicViewController::viewDidDisappear();
+  m_historyController->viewDidDisappear();
+}
+
 }

apps/calculation/edit_expression_controller.h

@@ -10,17 +10,17 @@
 namespace Calculation {
 class HistoryController;
 
+/* TODO: implement a split view */
 class EditExpressionController : public DynamicViewController, public Shared::TextFieldDelegate {
 public:
   EditExpressionController(Responder * parentResponder, HistoryController * historyController, CalculationStore * calculationStore);
   void didBecomeFirstResponder() override;
+  void viewDidDisappear() override;
   bool handleEvent(Ion::Events::Event event) override;
   const char * textBody();
   void setTextBody(const char * text);
   bool textFieldDidFinishEditing(::TextField * textField, const char * text, Ion::Events::Event event) override;
   bool textFieldDidAbortEditing(::TextField * textField, const char * text) override;
-  void loadView() override;
-  void unloadView() override;
 private:
   class ContentView : public View {
   public:
@@ -38,7 +38,8 @@ private:
     TextField m_textField;
     char m_textBody[TextField::maxBufferSize()];
   };
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   Shared::TextFieldDelegateApp * textFieldDelegateApp() override;
   HistoryController * m_historyController;
   CalculationStore * m_calculationStore;

apps/calculation/history_controller.cpp

@@ -171,29 +171,27 @@ int HistoryController::typeAtLocation(int i, int j) {
   return 0;
 }
 
-void HistoryController::unloadView() {
-  for (int i = 0; i < k_maxNumberOfDisplayedRows; i++) {
-    assert(m_calculationHistory[i] != nullptr);
-    delete m_calculationHistory[i];
-    m_calculationHistory[i] = nullptr;
-  }
-  DynamicViewController::unloadView();
-}
-
 void HistoryController::scrollToCell(int i, int j) {
   selectableTableView()->scrollToCell(i, j);
 }
 
-View * HistoryController::createView() {
-  for (int i = 0; i < k_maxNumberOfDisplayedRows; i++) {
-    assert(m_calculationHistory[i] == nullptr);
-    m_calculationHistory[i] = new HistoryViewCell();
-  }
-  return new CalculationSelectableTableView(this, this, this);
-}
-
 CalculationSelectableTableView * HistoryController::selectableTableView() {
   return (CalculationSelectableTableView *)view();
 }
 
+View * HistoryController::loadView() {
+  for (int i = 0; i < k_maxNumberOfDisplayedRows; i++) {
+    m_calculationHistory[i] = new HistoryViewCell();
+  }
+  return new CalculationSelectableTableView(this, this, this);
+}
+
+void HistoryController::unloadView(View * view) {
+  for (int i = 0; i < k_maxNumberOfDisplayedRows; i++) {
+    delete m_calculationHistory[i];
+    m_calculationHistory[i] = nullptr;
+  }
+  delete view;
+}
+
 }

apps/calculation/history_controller.h

@@ -28,10 +28,10 @@ public:
   int indexFromCumulatedHeight(KDCoordinate offsetY) override;
   int typeAtLocation(int i, int j) override;
   void tableViewDidChangeSelection(SelectableTableView * t, int previousSelectedCellX, int previousSelectedCellY) override;
-  void unloadView() override;
   void scrollToCell(int i, int j);
+  View * loadView() override;
+  void unloadView(View * view) override;
 private:
-  View * createView() override;
   CalculationSelectableTableView * selectableTableView();
   constexpr static int k_maxNumberOfDisplayedRows = 5;
   HistoryViewCell * m_calculationHistory[k_maxNumberOfDisplayedRows];

apps/graph/list/list_controller.cpp

@@ -36,18 +36,6 @@ KDCoordinate ListController::rowHeight(int j) {
   return functionSize + k_emptyRowHeight - KDText::stringSize(" ").height();
 }
 
-void ListController::unloadView() {
-  for (int i = 0; i < k_maxNumberOfRows; i++) {
-    assert(m_functionTitleCells[i] != nullptr);
-    delete m_functionTitleCells[i];
-    m_functionTitleCells[i] = nullptr;
-    assert(m_expressionCells[i] != nullptr);
-    delete m_expressionCells[i];
-    m_expressionCells[i] = nullptr;
-  }
-  Shared::ListController::unloadView();
-}
-
 void ListController::editExpression(Function * function, Ion::Events::Event event) {
   char * initialText = nullptr;
   char initialTextContent[TextField::maxBufferSize()];
@@ -111,14 +99,22 @@ void ListController::removeFunctionRow(Function * function) {
   }
 }
 
-View * ListController::createView() {
+View * ListController::loadView() {
   for (int i = 0; i < k_maxNumberOfRows; i++) {
-    assert(m_functionTitleCells[i] == nullptr);
     m_functionTitleCells[i] = new FunctionTitleCell(FunctionTitleCell::Orientation::VerticalIndicator);
-    assert(m_expressionCells[i] == nullptr);
     m_expressionCells[i] = new FunctionExpressionCell();
   }
-  return Shared::ListController::createView();
+  return Shared::ListController::loadView();
+}
+
+void ListController::unloadView(View * view) {
+  for (int i = 0; i < k_maxNumberOfRows; i++) {
+    delete m_functionTitleCells[i];
+    m_functionTitleCells[i] = nullptr;
+    delete m_expressionCells[i];
+    m_expressionCells[i] = nullptr;
+  }
+  Shared::ListController::unloadView(view);
 }
 
 }

apps/graph/list/list_controller.h

@@ -17,7 +17,6 @@ public:
   const char * title() override;
   int numberOfRows() override;
   KDCoordinate rowHeight(int j) override;
-  void unloadView() override;
 private:
   void editExpression(Shared::Function * function, Ion::Events::Event event) override;
   Shared::ListParameterController * parameterController() override;
@@ -27,7 +26,8 @@ private:
   void willDisplayTitleCellAtIndex(HighlightCell * cell, int j) override;
   void willDisplayExpressionCellAtIndex(HighlightCell * cell, int j) override;
   void removeFunctionRow(Shared::Function * function) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   constexpr static int k_maxNumberOfRows = 5;
   FunctionTitleCell * m_functionTitleCells[k_maxNumberOfRows];
   Shared::FunctionExpressionCell * m_expressionCells[k_maxNumberOfRows];

apps/graph/values/values_controller.cpp

@@ -81,20 +81,6 @@ IntervalParameterController * ValuesController::intervalParameterController() {
   return &m_intervalParameterController;
 }
 
-void ValuesController::unloadView() {
-  for (int i = 0; i < k_maxNumberOfCells; i++) {
-    assert(m_floatCells[i] != nullptr);
-    delete m_floatCells[i];
-    m_floatCells[i] = nullptr;
-  }
-  for (int i = 0; i < k_maxNumberOfFunctions; i++) {
-    assert(m_functionTitleCells[i] != nullptr);
-    delete m_functionTitleCells[i];
-    m_functionTitleCells[i] = nullptr;
-  }
-  Shared::ValuesController::unloadView();
-}
-
 CartesianFunction * ValuesController::functionAtColumn(int i) {
   assert(i > 0);
   int index = 1;
@@ -179,16 +165,26 @@ float ValuesController::evaluationOfAbscissaAtColumn(float abscissa, int columnI
   return function->evaluateAtAbscissa(abscissa, myApp->localContext());
 }
 
-View * ValuesController::createView() {
+View * ValuesController::loadView() {
   for (int i = 0; i < k_maxNumberOfFunctions; i++) {
-    assert(m_functionTitleCells[i] == nullptr);
     m_functionTitleCells[i] = new FunctionTitleCell(FunctionTitleCell::Orientation::HorizontalIndicator, KDText::FontSize::Small);
   }
   for (int i = 0; i < k_maxNumberOfCells; i++) {
-    assert(m_floatCells[i] == nullptr);
     m_floatCells[i] = new EvenOddBufferTextCell();
   }
-  return Shared::ValuesController::createView();
+  return Shared::ValuesController::loadView();
+}
+
+void ValuesController::unloadView(View * view) {
+  for (int i = 0; i < k_maxNumberOfCells; i++) {
+    delete m_floatCells[i];
+    m_floatCells[i] = nullptr;
+  }
+  for (int i = 0; i < k_maxNumberOfFunctions; i++) {
+    delete m_functionTitleCells[i];
+    m_functionTitleCells[i] = nullptr;
+  }
+  Shared::ValuesController::unloadView(view);
 }
 
 }

apps/graph/values/values_controller.h

@@ -20,7 +20,6 @@ public:
   int activeRow();
   int activeColumn();
   Shared::IntervalParameterController * intervalParameterController() override;
-  void unloadView() override;
 private:
   CartesianFunction * functionAtColumn(int i) override;
   bool isDerivativeColumn(int i);
@@ -38,7 +37,8 @@ private:
   CartesianFunctionStore * functionStore() const override;
   FunctionParameterController m_functionParameterController;
   FunctionParameterController * functionParameterController() override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   Shared::IntervalParameterController m_intervalParameterController;
   DerivativeParameterController m_derivativeParameterController;
 };

apps/main.cpp

@@ -5,4 +5,5 @@ AppsContainer container;
 void ion_app() {
   container.switchTo(container.appAtIndex(0));
   container.run();
+  container.switchTo(nullptr);
 }

apps/math_toolbox.cpp

@@ -221,6 +221,7 @@ void MathToolbox::viewWillAppear() {
 }
 
 void MathToolbox::viewDidDisappear() {
+  Toolbox::viewDidDisappear();
   m_selectableTableView.deselectTable();
 }
 

apps/probability/parameters_controller.cpp

@@ -87,11 +87,11 @@ void ParametersController::setLaw(Law * law) {
 }
 
 void ParametersController::viewWillAppear() {
+  FloatParameterController::viewWillAppear();
   for (int i = 0; i < m_law->numberOfParameter(); i++) {
     contentView()->parameterDefinitionAtIndex(i)->setMessage(m_law->parameterDefinitionAtIndex(i));
   }
   contentView()->layoutSubviews();
-  FloatParameterController::viewWillAppear();
 }
 
 int ParametersController::numberOfRows() {
@@ -120,18 +120,6 @@ int ParametersController::reusableParameterCellCount(int type) {
   return m_law->numberOfParameter();
 }
 
-void ParametersController::unloadView() {
-  assert(m_selectableTableView != nullptr);
-  delete m_selectableTableView;
-  m_selectableTableView = nullptr;
-  for (int i = 0; i < k_maxNumberOfCells; i++) {
-    assert(m_menuListCell[i] != nullptr);
-    delete m_menuListCell[i];
-    m_menuListCell[i] = nullptr;
-  }
-  FloatParameterController::unloadView();
-}
-
 float ParametersController::parameterAtIndex(int index) {
   return m_law->parameterValueAtIndex(index);
 }
@@ -165,11 +153,9 @@ I18n::Message ParametersController::okButtonText() {
   return I18n::Message::Next;
 }
 
-View * ParametersController::createView() {
-  assert(m_selectableTableView == nullptr);
-  m_selectableTableView = (SelectableTableView *)FloatParameterController::createView();
+View * ParametersController::loadView() {
+  m_selectableTableView = (SelectableTableView *)FloatParameterController::loadView();
   for (int i = 0; i < k_maxNumberOfCells; i++) {
-    assert(m_menuListCell[i] == nullptr);
     m_menuListCell[i] = new MessageTableCellWithEditableText(m_selectableTableView, this, m_draftTextBuffer);
   }
   ContentView * contentView = (ContentView *)new ContentView(this, m_selectableTableView);
@@ -179,6 +165,16 @@ View * ParametersController::createView() {
   return contentView;
 }
 
+void ParametersController::unloadView(View * view) {
+  delete m_selectableTableView;
+  m_selectableTableView = nullptr;
+  for (int i = 0; i < k_maxNumberOfCells; i++) {
+    delete m_menuListCell[i];
+    m_menuListCell[i] = nullptr;
+  }
+  FloatParameterController::unloadView(view);
+}
+
 SelectableTableView * ParametersController::selectableTableView() {
   return m_selectableTableView;
 }

apps/probability/parameters_controller.h

@@ -16,7 +16,6 @@ public:
   void viewWillAppear() override;
   int numberOfRows() override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
-  void unloadView() override;
 private:
   HighlightCell * reusableParameterCell(int index, int type) override;
   int reusableParameterCellCount(int type) override;
@@ -25,7 +24,8 @@ private:
   bool setParameterAtIndex(int parameterIndex, float f) override;
   bool textFieldDidFinishEditing(TextField * textField, const char * text, Ion::Events::Event event) override;
   I18n::Message okButtonText() override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   class ContentView : public View {
   public:
     ContentView(Responder * parentResponder, SelectableTableView * selectableTableView);

apps/regression/calculation_controller.cpp

@@ -231,54 +231,44 @@ int CalculationController::typeAtLocation(int i, int j) {
   return 4;
 }
 
-void CalculationController::unloadView() {
-  assert(m_r2TitleCell != nullptr);
-  delete m_r2TitleCell;
-  m_r2TitleCell = nullptr;
-  assert(m_columnTitleCell != nullptr);
-  delete m_columnTitleCell;
-  m_columnTitleCell = nullptr;
-  for (int i = 0; i < k_maxNumberOfDisplayableRows/2; i++) {
-    assert(m_doubleCalculationCells[i] != nullptr);
-    delete m_doubleCalculationCells[i];
-    m_doubleCalculationCells[i] = nullptr;
-    assert(m_calculationCells[i] != nullptr);
-    delete m_calculationCells[i];
-    m_calculationCells[i] = nullptr;
-  }
-  for (int i = 0; i < k_maxNumberOfDisplayableRows; i++) {
-    assert(m_titleCells[i] != nullptr);
-    delete m_titleCells[i];
-    m_titleCells[i] = nullptr;
-  }
-  TabTableController::unloadView();
-}
-
 Responder * CalculationController::tabController() const {
   return (parentResponder()->parentResponder()->parentResponder());
 }
 
-View * CalculationController::createView() {
-  SelectableTableView * tableView = (SelectableTableView *)TabTableController::createView();
-  assert(m_r2TitleCell == nullptr);
+View * CalculationController::loadView() {
+  SelectableTableView * tableView = (SelectableTableView *)TabTableController::loadView();
   m_r2TitleCell = new EvenOddExpressionCell(1.0f, 0.5f);
-  assert(m_columnTitleCell == nullptr);
   m_columnTitleCell = new EvenOddDoubleBufferTextCell(tableView);
   for (int i = 0; i < k_maxNumberOfDisplayableRows; i++) {
-    assert(m_titleCells[i] == nullptr);
     m_titleCells[i] = new EvenOddMessageTextCell(KDText::FontSize::Small);
   }
   for (int i = 0; i < k_maxNumberOfDisplayableRows/2; i++) {
-    assert(m_doubleCalculationCells[i] == nullptr);
     m_doubleCalculationCells[i] = new EvenOddDoubleBufferTextCell();
     m_doubleCalculationCells[i]->setTextColor(Palette::GreyDark);
     m_doubleCalculationCells[i]->setParentResponder(tableView);
-    assert(m_calculationCells[i] == nullptr);
     m_calculationCells[i] = new EvenOddBufferTextCell(KDText::FontSize::Small);
     m_calculationCells[i]->setTextColor(Palette::GreyDark);
   }
   return tableView;
 }
 
+void CalculationController::unloadView(View * view) {
+  delete m_r2TitleCell;
+  m_r2TitleCell = nullptr;
+  delete m_columnTitleCell;
+  m_columnTitleCell = nullptr;
+  for (int i = 0; i < k_maxNumberOfDisplayableRows/2; i++) {
+    delete m_doubleCalculationCells[i];
+    m_doubleCalculationCells[i] = nullptr;
+    delete m_calculationCells[i];
+    m_calculationCells[i] = nullptr;
+  }
+  for (int i = 0; i < k_maxNumberOfDisplayableRows; i++) {
+    delete m_titleCells[i];
+    m_titleCells[i] = nullptr;
+  }
+  TabTableController::unloadView(view);
+}
+
 }
 

apps/regression/calculation_controller.h

@@ -31,10 +31,10 @@ public:
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   int typeAtLocation(int i, int j) override;
-  void unloadView() override;
 private:
   Responder * tabController() const override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   constexpr static int k_totalNumberOfRows = 11;
   constexpr static int k_totalNumberOfColumns = 2;
   constexpr static int k_maxNumberOfDisplayableRows = 10;

apps/regression/store_controller.cpp

@@ -36,26 +36,24 @@ void StoreController::willDisplayCellAtLocation(HighlightCell * cell, int i, int
   mytitleCell->setExpression(m_titleLayout[i]);
 }
 
-void StoreController::unloadView() {
-  for (int i = 0; i < k_numberOfTitleCells; i++) {
-    assert(m_titleCells[i] != nullptr);
-    delete m_titleCells[i];
-    m_titleCells[i] = nullptr;
-  }
-  Shared::StoreController::unloadView();
-}
-
 HighlightCell * StoreController::titleCells(int index) {
   assert(index >= 0 && index < k_numberOfTitleCells);
   return m_titleCells[index];
 }
 
-View * StoreController::createView() {
+View * StoreController::loadView() {
   for (int i = 0; i < k_numberOfTitleCells; i++) {
-    assert(m_titleCells[i] == nullptr);
     m_titleCells[i] = new EvenOddExpressionCell(0.5f, 0.5f);
   }
-  return Shared::StoreController::createView();
+  return Shared::StoreController::loadView();
+}
+
+void StoreController::unloadView(View * view) {
+  for (int i = 0; i < k_numberOfTitleCells; i++) {
+    delete m_titleCells[i];
+    m_titleCells[i] = nullptr;
+  }
+  Shared::StoreController::unloadView(view);
 }
 
 }

apps/regression/store_controller.h

@@ -12,10 +12,10 @@ public:
   StoreController(Responder * parentResponder, Store * store, ButtonRowController * header);
   ~StoreController();
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
-  void unloadView() override;
 private:
   HighlightCell * titleCells(int index) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   EvenOddExpressionCell * m_titleCells[k_numberOfTitleCells];
   Poincare::ExpressionLayout * m_titleLayout[2];
 };

apps/sequence/list/list_controller.cpp

@@ -80,18 +80,6 @@ void ListController::selectPreviousNewSequenceCell() {
   }
 }
 
-void ListController::unloadView() {
-  for (int i = 0; i < k_maxNumberOfRows; i++) {
-    assert(m_sequenceTitleCells[i] != nullptr);
-    delete m_sequenceTitleCells[i];
-    m_sequenceTitleCells[i] = nullptr;
-    assert(m_expressionCells[i] != nullptr);
-    delete m_expressionCells[i];
-    m_expressionCells[i] = nullptr;
-  }
-  Shared::ListController::unloadView();
-}
-
 void ListController::editExpression(Sequence * sequence, int sequenceDefinition, Ion::Events::Event event) {
   char * initialText = nullptr;
   char initialTextContent[TextField::maxBufferSize()];
@@ -276,14 +264,22 @@ void ListController::reinitExpression(Shared::Function * function) {
   selectableTableView()->reloadData();
 }
 
-View * ListController::createView() {
+View * ListController::loadView() {
   for (int i = 0; i < k_maxNumberOfRows; i++) {
-    assert(m_sequenceTitleCells[i] == nullptr);
     m_sequenceTitleCells[i] = new SequenceTitleCell(FunctionTitleCell::Orientation::VerticalIndicator);
-    assert(m_expressionCells[i] == nullptr);
     m_expressionCells[i] = new FunctionExpressionCell();
   }
-  return Shared::ListController::createView();
+  return Shared::ListController::loadView();
+}
+
+void ListController::unloadView(View * view) {
+  for (int i = 0; i < k_maxNumberOfRows; i++) {
+    delete m_sequenceTitleCells[i];
+    m_sequenceTitleCells[i] = nullptr;
+    delete m_expressionCells[i];
+    m_expressionCells[i] = nullptr;
+  }
+  Shared::ListController::unloadView(view);
 }
 
 }

apps/sequence/list/list_controller.h

@@ -23,7 +23,6 @@ public:
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   Toolbox * toolboxForTextField(TextField * textField) override;
   void selectPreviousNewSequenceCell();
-  void unloadView() override;
 private:
   Shared::TextFieldDelegateApp * textFieldDelegateApp() override;
   void editExpression(Sequence * sequence, int sequenceDefinitionIndex, Ion::Events::Event event);
@@ -39,7 +38,8 @@ private:
   void addEmptyFunction() override;
   void editExpression(Shared::Function * function, Ion::Events::Event event) override;
   void reinitExpression(Shared::Function * function) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   static constexpr KDCoordinate k_emptySubRowHeight = 30;
   constexpr static int k_maxNumberOfRows = 9;
   SequenceStore * m_sequenceStore;

apps/sequence/values/values_controller.cpp

@@ -47,20 +47,6 @@ IntervalParameterController * ValuesController::intervalParameterController() {
   return &m_intervalParameterController;
 }
 
-void ValuesController::unloadView() {
-  for (int i = 0; i < k_maxNumberOfCells; i++) {
-    assert(m_floatCells[i] != nullptr);
-    delete m_floatCells[i];
-    m_floatCells[i] = nullptr;
-  }
-  for (int i = 0; i < k_maxNumberOfSequences; i++) {
-    assert(m_sequenceTitleCells[i] != nullptr);
-    delete m_sequenceTitleCells[i];
-    m_sequenceTitleCells[i] = nullptr;
-  }
-  Shared::ValuesController::unloadView();
-}
-
 bool ValuesController::setDataAtLocation(float floatBody, int columnIndex, int rowIndex) {
   if (floatBody < 0) {
       return false;
@@ -98,16 +84,26 @@ Shared::ValuesFunctionParameterController * ValuesController::functionParameterC
 #endif
 }
 
-View * ValuesController::createView() {
+View * ValuesController::loadView() {
   for (int i = 0; i < k_maxNumberOfSequences; i++) {
-    assert(m_sequenceTitleCells[i] == nullptr);
     m_sequenceTitleCells[i] = new SequenceTitleCell(FunctionTitleCell::Orientation::HorizontalIndicator);
   }
   for (int i = 0; i < k_maxNumberOfCells; i++) {
-    assert(m_floatCells[i] == nullptr);
     m_floatCells[i] = new EvenOddBufferTextCell();
   }
-  return Shared::ValuesController::createView();
+  return Shared::ValuesController::loadView();
+}
+
+void ValuesController::unloadView(View * view) {
+  for (int i = 0; i < k_maxNumberOfCells; i++) {
+    delete m_floatCells[i];
+    m_floatCells[i] = nullptr;
+  }
+  for (int i = 0; i < k_maxNumberOfSequences; i++) {
+    delete m_sequenceTitleCells[i];
+    m_sequenceTitleCells[i] = nullptr;
+  }
+  Shared::ValuesController::unloadView(view);
 }
 
 }

apps/sequence/values/values_controller.h

@@ -15,7 +15,6 @@ public:
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   I18n::Message emptyMessage() override;
   IntervalParameterController * intervalParameterController() override;
-  void unloadView() override;
 private:
   bool setDataAtLocation(float floatBody, int columnIndex, int rowIndex) override;
   int maxNumberOfCells() override;
@@ -28,7 +27,8 @@ private:
   EvenOddBufferTextCell * floatCells(int j) override;
   SequenceStore * m_sequenceStore;
   SequenceStore * functionStore() const override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
 #if COPY_COLUMN
   Shared::ValuesFunctionParameterController m_sequenceParameterController;
 #endif

apps/shared/editable_cell_table_view_controller.cpp

@@ -114,8 +114,7 @@ void EditableCellTableViewController::didBecomeFirstResponder() {
   }
 }
 
-void EditableCellTableViewController::viewWillAppear() {
-  TabTableController::viewWillAppear();
+void EditableCellTableViewController::didEnterResponderChain(Responder * previousFirstResponder) {
   if (selectedRow() == -1) {
     selectCellAtLocation(0, 1);
   } else {

apps/shared/editable_cell_table_view_controller.h

@@ -22,7 +22,7 @@ public:
   KDCoordinate rowHeight(int j) override;
 
   void didBecomeFirstResponder() override;
-  void viewWillAppear() override;
+  void didEnterResponderChain(Responder * previousFirstResponder) override;
 private:
   TextFieldDelegateApp * textFieldDelegateApp() override;
   static constexpr KDCoordinate k_cellHeight = 20;

apps/shared/float_parameter_controller.cpp

@@ -25,6 +25,7 @@ void FloatParameterController::didBecomeFirstResponder() {
 }
 
 void FloatParameterController::viewWillAppear() {
+  DynamicViewController::viewWillAppear();
   selectableTableView()->reloadData();
   if (selectedRow() == -1) {
     selectCellAtLocation(0, 0);
@@ -169,13 +170,6 @@ int FloatParameterController::activeCell() {
   return selectedRow();
 }
 
-void FloatParameterController::unloadView() {
-  assert(m_okButton != nullptr);
-  delete m_okButton;
-  m_okButton = nullptr;
-  DynamicViewController::unloadView();
-}
-
 StackViewController * FloatParameterController::stackController() {
   return (StackViewController *)parentResponder();
 }
@@ -184,16 +178,6 @@ SelectableTableView * FloatParameterController::selectableTableView() {
   return (SelectableTableView *)view();
 }
 
-View * FloatParameterController::createView() {
-  SelectableTableView * tableView = new SelectableTableView(this, this, 0, 1, Metric::CommonTopMargin, Metric::CommonRightMargin, Metric::CommonBottomMargin, Metric::CommonLeftMargin, this);
-  assert(m_okButton == nullptr);
-  m_okButton = new ButtonWithSeparator(tableView, okButtonText(), Invocation([](void * context, void * sender) {
-    FloatParameterController * parameterController = (FloatParameterController *) context;
-    parameterController->buttonAction();
-  }, this));
-  return tableView;
-}
-
 void FloatParameterController::buttonAction() {
   StackViewController * stack = stackController();
   stack->pop();
@@ -203,4 +187,19 @@ I18n::Message FloatParameterController::okButtonText() {
   return I18n::Message::Ok;
 }
 
+View * FloatParameterController::loadView() {
+  SelectableTableView * tableView = new SelectableTableView(this, this, 0, 1, Metric::CommonTopMargin, Metric::CommonRightMargin, Metric::CommonBottomMargin, Metric::CommonLeftMargin, this);
+  m_okButton = new ButtonWithSeparator(tableView, okButtonText(), Invocation([](void * context, void * sender) {
+    FloatParameterController * parameterController = (FloatParameterController *) context;
+    parameterController->buttonAction();
+  }, this));
+  return tableView;
+}
+
+void FloatParameterController::unloadView(View * view) {
+  delete m_okButton;
+  m_okButton = nullptr;
+  delete view;
+}
+
 }

apps/shared/float_parameter_controller.h

@@ -29,13 +29,13 @@ public:
   bool textFieldDidFinishEditing(TextField * textField, const char * text, Ion::Events::Event event) override;
   bool textFieldDidReceiveEvent(TextField * textField, Ion::Events::Event event) override;
   void tableViewDidChangeSelection(SelectableTableView * t, int previousSelectedCellX, int previousSelectedCellY) override;
-  void unloadView() override;
 protected:
   int activeCell();
   StackViewController * stackController();
   virtual float parameterAtIndex(int index) = 0;
   virtual SelectableTableView * selectableTableView();
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
 private:
   constexpr static int k_buttonMargin = 6;
   virtual void buttonAction();

apps/shared/go_to_parameter_controller.cpp

@@ -16,13 +16,6 @@ int GoToParameterController::numberOfRows() {
   return 2;
 }
 
-void GoToParameterController::unloadView() {
-  assert(m_abscisseCell != nullptr);
-  delete m_abscisseCell;
-  m_abscisseCell = nullptr;
-  FloatParameterController::unloadView();
-}
-
 HighlightCell * GoToParameterController::reusableParameterCell(int index, int type) {
   assert(index == 0);
   return m_abscisseCell;
@@ -40,11 +33,16 @@ void GoToParameterController::buttonAction() {
   stack->pop();
 }
 
-View * GoToParameterController::createView() {
-  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::createView();
-  assert(m_abscisseCell == nullptr);
+View * GoToParameterController::loadView() {
+  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::loadView();
   m_abscisseCell = new MessageTableCellWithEditableText(tableView, this, m_draftTextBuffer, m_abscissaSymbol);
   return tableView;
 }
 
+void GoToParameterController::unloadView(View * view) {
+  delete m_abscisseCell;
+  m_abscisseCell = nullptr;
+  FloatParameterController::unloadView(view);
+}
+
 }

apps/shared/go_to_parameter_controller.h

@@ -12,7 +12,6 @@ class GoToParameterController : public FloatParameterController {
 public:
   GoToParameterController(Responder * parentResponder, InteractiveCurveViewRange * graphRange, CurveViewCursor * cursor, I18n::Message symbol);
   int numberOfRows() override;
-  void unloadView() override;
 protected:
   constexpr static float k_maxDisplayableFloat = 1E8f;
   CurveViewCursor * m_cursor;
@@ -20,7 +19,8 @@ private:
   void buttonAction() override;
   HighlightCell * reusableParameterCell(int index, int type) override;
   int reusableParameterCellCount(int type) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   char m_draftTextBuffer[MessageTableCellWithEditableText::k_bufferLength];
   MessageTableCellWithEditableText * m_abscisseCell;
   InteractiveCurveViewRange * m_graphRange;

apps/shared/interval_parameter_controller.cpp

@@ -31,15 +31,6 @@ Interval * IntervalParameterController::interval() {
   return m_interval;
 }
 
-void IntervalParameterController::unloadView() {
-  for (int i = 0; i < k_totalNumberOfCell; i++) {
-    assert(m_intervalCells[i] != nullptr);
-    delete m_intervalCells[i];
-    m_intervalCells[i] = nullptr;
-  }
-  FloatParameterController::unloadView();
-}
-
 float IntervalParameterController::parameterAtIndex(int index) {
   GetterPointer getters[k_totalNumberOfCell] = {&Interval::start, &Interval::end, &Interval::step};
   return (m_interval->*getters[index])();
@@ -75,13 +66,20 @@ int IntervalParameterController::reusableParameterCellCount(int type) {
   return k_totalNumberOfCell;
 }
 
-View * IntervalParameterController::createView() {
-  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::createView();
+View * IntervalParameterController::loadView() {
+  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::loadView();
   for (int i = 0; i < k_totalNumberOfCell; i++) {
-    assert(m_intervalCells[i] == nullptr);
     m_intervalCells[i] = new MessageTableCellWithEditableText(tableView, this, m_draftTextBuffer, I18n::Message::Default);
   }
   return tableView;
 }
 
+void IntervalParameterController::unloadView(View * view) {
+  for (int i = 0; i < k_totalNumberOfCell; i++) {
+    delete m_intervalCells[i];
+    m_intervalCells[i] = nullptr;
+  }
+  FloatParameterController::unloadView(view);
+}
+
 }

apps/shared/interval_parameter_controller.h

@@ -14,7 +14,6 @@ public:
   const char * title() override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
   int numberOfRows() override;
-  void unloadView() override;
 protected:
   constexpr static int k_totalNumberOfCell = 3;
   bool setParameterAtIndex(int parameterIndex, float f) override;
@@ -23,7 +22,8 @@ private:
   HighlightCell * reusableParameterCell(int index, int type) override;
   int reusableParameterCellCount(int type) override;
   float parameterAtIndex(int index) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   char m_draftTextBuffer[MessageTableCellWithEditableText::k_bufferLength];
   MessageTableCellWithEditableText * m_intervalCells[k_totalNumberOfCell];
 };

apps/shared/list_controller.cpp

@@ -235,7 +235,7 @@ bool ListController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-void ListController::viewWillAppear() {
+void ListController::didEnterResponderChain(Responder * previousFirstResponder) {
   selectableTableView()->reloadData();
 }
 
@@ -246,16 +246,6 @@ void ListController::willExitResponderChain(Responder * nextFirstResponder) {
   }
 }
 
-void ListController::unloadView() {
-  assert(m_emptyCell != nullptr);
-  delete m_emptyCell;
-  m_emptyCell = nullptr;
-  assert(m_addNewFunction != nullptr);
-  delete m_addNewFunction;
-  m_addNewFunction = nullptr;
-  DynamicViewController::unloadView();
-}
-
 StackViewController * ListController::stackController() const{
   return (StackViewController *)(parentResponder()->parentResponder()->parentResponder());
 }
@@ -275,14 +265,6 @@ SelectableTableView * ListController::selectableTableView() {
   return (SelectableTableView *)view();
 }
 
-View * ListController::createView() {
-  assert(m_emptyCell == nullptr);
-  m_emptyCell = new EvenOddCell();
-  assert(m_addNewFunction == nullptr);
-  m_addNewFunction = new NewFunctionCell(m_addNewMessage);
-  return new SelectableTableView(this, this, 0, 0, 0, 0, 0, 0, this, false, true);
-}
-
 TabViewController * ListController::tabController() const{
   return (TabViewController *)(parentResponder()->parentResponder()->parentResponder()->parentResponder());
 }
@@ -305,4 +287,18 @@ void ListController::removeFunctionRow(Function * function) {
   m_functionStore->removeFunction(function);
 }
 
+View * ListController::loadView() {
+  m_emptyCell = new EvenOddCell();
+  m_addNewFunction = new NewFunctionCell(m_addNewMessage);
+  return new SelectableTableView(this, this, 0, 0, 0, 0, 0, 0, this, false, true);
+}
+
+void ListController::unloadView(View * view) {
+  delete m_emptyCell;
+  m_emptyCell = nullptr;
+  delete m_addNewFunction;
+  m_addNewFunction = nullptr;
+  delete view;
+}
+
 }

apps/shared/list_controller.h

@@ -26,16 +26,16 @@ public:
   Button * buttonAtIndex(int index, ButtonRowController::Position position) const override;
   void didBecomeFirstResponder() override;
   bool handleEvent(Ion::Events::Event event) override;
-  void viewWillAppear() override;
+  void didEnterResponderChain(Responder * previousFirstResponder) override;
   void willExitResponderChain(Responder * nextFirstResponder) override;
-  void unloadView() override;
 protected:
   static constexpr KDCoordinate k_emptyRowHeight = 50;
   StackViewController * stackController() const;
   void configureFunction(Function * function);
   virtual void reinitExpression(Function * function);
   SelectableTableView * selectableTableView();
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   FunctionStore * m_functionStore;
 private:
   static constexpr KDCoordinate k_functionNameWidth = 65;

apps/shared/range_parameter_controller.cpp

@@ -121,28 +121,24 @@ int RangeParameterController::reusableParameterCellCount(int type) {
   return k_numberOfTextCell;
 }
 
-void RangeParameterController::unloadView() {
-  assert(m_yAutoCell != nullptr);
-  delete m_yAutoCell;
-  m_yAutoCell = nullptr;
-  for (int i = 0; i < k_numberOfTextCell; i++) {
-    assert(m_rangeCells[i] != nullptr);
-    delete m_rangeCells[i];
-    m_rangeCells[i] = nullptr;
-  }
-  FloatParameterController::unloadView();
-}
-
-View * RangeParameterController::createView() {
-  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::createView();
-  assert(m_yAutoCell == nullptr);
+View * RangeParameterController::loadView() {
+  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::loadView();
   m_yAutoCell = new MessageTableCellWithSwitch(I18n::Message::YAuto);
   for (int i = 0; i < k_numberOfTextCell; i++) {
-    assert(m_rangeCells[i] == nullptr);
     m_rangeCells[i] = new MessageTableCellWithEditableText(tableView, this, m_draftTextBuffer, I18n::Message::Default);
   }
   return tableView;
 }
 
+void RangeParameterController::unloadView(View * view) {
+  delete m_yAutoCell;
+  m_yAutoCell = nullptr;
+  for (int i = 0; i < k_numberOfTextCell; i++) {
+    delete m_rangeCells[i];
+    m_rangeCells[i] = nullptr;
+  }
+  FloatParameterController::unloadView(view);
+}
+
 }
 

apps/shared/range_parameter_controller.h

@@ -17,13 +17,13 @@ public:
   bool textFieldDidFinishEditing(TextField * textField, const char * text, Ion::Events::Event event) override;
   void tableViewDidChangeSelection(SelectableTableView * t, int previousSelectedCellX, int previousSelectedCellY) override;
   bool handleEvent(Ion::Events::Event event) override;
-  void unloadView() override;
 private:
   HighlightCell * reusableParameterCell(int index, int type) override;
   int reusableParameterCellCount(int type) override;
   float parameterAtIndex(int index) override;
   bool setParameterAtIndex(int parameterIndex, float f) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   constexpr static int k_numberOfTextCell = 4;
   InteractiveCurveViewRange * m_interactiveRange;
   char m_draftTextBuffer[MessageTableCellWithEditableText::k_bufferLength];

apps/shared/store_controller.cpp

@@ -96,15 +96,6 @@ bool StoreController::handleEvent(Ion::Events::Event event) {
   return false;
 }
 
-void StoreController::unloadView() {
-  for (int i = 0; i < k_maxNumberOfEditableCells; i++) {
-    assert(m_editableCells[i] != nullptr);
-    delete m_editableCells[i];
-    m_editableCells[i] = nullptr;
-  }
-  EditableCellTableViewController::unloadView();
-}
-
 Responder * StoreController::tabController() const {
   return (parentResponder()->parentResponder()->parentResponder());
 }
@@ -133,13 +124,20 @@ int StoreController::maxNumberOfElements() const {
   return FloatPairStore::k_maxNumberOfPairs;
 }
 
-View * StoreController::createView() {
-  SelectableTableView * tableView = (SelectableTableView*)EditableCellTableViewController::createView();
+View * StoreController::loadView() {
+  SelectableTableView * tableView = (SelectableTableView*)EditableCellTableViewController::loadView();
   for (int i = 0; i < k_maxNumberOfEditableCells; i++) {
-    assert(m_editableCells[i] == nullptr);
     m_editableCells[i] = new EvenOddEditableTextCell(tableView, this, m_draftTextBuffer);
   }
   return tableView;
 }
 
+void StoreController::unloadView(View * view) {
+  for (int i = 0; i < k_maxNumberOfEditableCells; i++) {
+    delete m_editableCells[i];
+    m_editableCells[i] = nullptr;
+  }
+  EditableCellTableViewController::unloadView(view);
+}
+
 }

apps/shared/store_controller.h

@@ -22,13 +22,13 @@ public:
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
-  void unloadView() override;
 protected:
   static constexpr KDCoordinate k_cellWidth = Ion::Display::Width/2 - Metric::CommonRightMargin/2 - Metric::CommonLeftMargin/2;
   constexpr static int k_maxNumberOfEditableCells = 22;
   constexpr static int k_numberOfTitleCells = 2;
   Responder * tabController() const override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   bool cellAtLocationIsEditable(int columnIndex, int rowIndex) override;
   bool setDataAtLocation(float floatBody, int columnIndex, int rowIndex) override;
   float dataAtLocation(int columnIndex, int rowIndex) override;

apps/shared/tab_table_controller.cpp

@@ -19,6 +19,7 @@ void TabTableController::didBecomeFirstResponder() {
 }
 
 void TabTableController::viewWillAppear() {
+  DynamicViewController::viewWillAppear();
   selectableTableView()->reloadData();
 }
 
@@ -33,10 +34,13 @@ SelectableTableView * TabTableController::selectableTableView() {
   return (SelectableTableView *)view();
 }
 
-View * TabTableController::createView() {
+View * TabTableController::loadView() {
   return new SelectableTableView(this, m_dataSource, 0, 0, m_topMargin, m_rightMargin, m_bottomMargin, m_leftMargin, this, m_showIndicators, true, Palette::WallScreenDark);
 }
 
+void TabTableController::unloadView(View * view) {
+  delete view;
+}
 
 }
 

apps/shared/tab_table_controller.h

@@ -17,7 +17,8 @@ public:
   void willExitResponderChain(Responder * nextFirstResponder) override;
 protected:
   SelectableTableView * selectableTableView();
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   virtual Responder * tabController() const = 0;
 private:
   TableViewDataSource * m_dataSource;

apps/shared/values_controller.cpp

@@ -227,20 +227,8 @@ Responder * ValuesController::defaultController() {
 }
 
 void ValuesController::viewWillAppear() {
-  header()->setSelectedButton(-1);
   EditableCellTableViewController::viewWillAppear();
-}
-
-void ValuesController::unloadView() {
-  assert(m_abscissaTitleCell != nullptr);
-  delete m_abscissaTitleCell;
-  m_abscissaTitleCell = nullptr;
-  for (int i = 0; i < k_maxNumberOfAbscissaCells; i++) {
-    assert(m_abscissaCells[i] != nullptr);
-    delete m_abscissaCells[i];
-    m_abscissaCells[i] = nullptr;
-  }
-  EditableCellTableViewController::unloadView();
+  header()->setSelectedButton(-1);
 }
 
 Function * ValuesController::functionAtColumn(int i) {
@@ -305,16 +293,24 @@ float ValuesController::evaluationOfAbscissaAtColumn(float abscissa, int columnI
   return function->evaluateAtAbscissa(abscissa, myApp->localContext());
 }
 
-View * ValuesController::createView() {
-  SelectableTableView * tableView = (SelectableTableView*)EditableCellTableViewController::createView();
-  assert(m_abscissaTitleCell == nullptr);
+View * ValuesController::loadView() {
+  SelectableTableView * tableView = (SelectableTableView*)EditableCellTableViewController::loadView();
   m_abscissaTitleCell = new EvenOddMessageTextCell(KDText::FontSize::Small);
   for (int i = 0; i < k_maxNumberOfAbscissaCells; i++) {
-    assert(m_abscissaCells[i] == nullptr);
     m_abscissaCells[i] = new EvenOddEditableTextCell(tableView, this, m_draftTextBuffer, KDText::FontSize::Small);
   }
   return tableView;
 }
 
+void ValuesController::unloadView(View * view) {
+  delete m_abscissaTitleCell;
+  m_abscissaTitleCell = nullptr;
+  for (int i = 0; i < k_maxNumberOfAbscissaCells; i++) {
+    delete m_abscissaCells[i];
+    m_abscissaCells[i] = nullptr;
+  }
+  EditableCellTableViewController::unloadView(view);
+}
+
 }
 

apps/shared/values_controller.h

@@ -34,7 +34,6 @@ public:
   bool isEmpty() const override;
   Responder * defaultController() override;
   void viewWillAppear() override;
-  void unloadView() override;
   static constexpr KDCoordinate k_topMargin = 10;
   static constexpr KDCoordinate k_bottomMargin = 5;
   static constexpr KDCoordinate k_leftMargin = 1;
@@ -44,7 +43,8 @@ public:
 protected:
   StackViewController * stackController() const;
   bool setDataAtLocation(float floatBody, int columnIndex, int rowIndex) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   Interval m_interval;
 private:
   virtual Function * functionAtColumn(int i);

apps/statistics/calculation_controller.cpp

@@ -111,32 +111,29 @@ int CalculationController::typeAtLocation(int i, int j) {
   return i;
 }
 
-void CalculationController::unloadView() {
-  for (int i = 0; i < k_maxNumberOfDisplayableRows; i++) {
-    assert(m_titleCells[i] != nullptr);
-    delete m_titleCells[i];
-    m_titleCells[i] = nullptr;
-    assert(m_calculationCells[i] != nullptr);
-    delete m_calculationCells[i];
-    m_calculationCells[i] = nullptr;
-  }
-  TabTableController::unloadView();
-}
-
 Responder * CalculationController::tabController() const {
   return (parentResponder()->parentResponder()->parentResponder());
 }
 
-View * CalculationController::createView() {
+View * CalculationController::loadView() {
   for (int i = 0; i < k_maxNumberOfDisplayableRows; i++) {
-    assert(m_titleCells[i] == nullptr);
     m_titleCells[i] = new EvenOddMessageTextCell(KDText::FontSize::Small);
     m_titleCells[i]->setAlignment(1.0f, 0.5f);
-    assert(m_calculationCells[i] == nullptr);
     m_calculationCells[i] = new EvenOddBufferTextCell(KDText::FontSize::Small);
     m_calculationCells[i]->setTextColor(Palette::GreyDark);
   }
-  return TabTableController::createView();
+  return TabTableController::loadView();
+}
+
+
+void CalculationController::unloadView(View * view) {
+  for (int i = 0; i < k_maxNumberOfDisplayableRows; i++) {
+    delete m_titleCells[i];
+    m_titleCells[i] = nullptr;
+    delete m_calculationCells[i];
+    m_calculationCells[i] = nullptr;
+  }
+  TabTableController::unloadView(view);
 }
 
 }

apps/statistics/calculation_controller.h

@@ -29,10 +29,10 @@ public:
   HighlightCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   int typeAtLocation(int i, int j) override;
-  void unloadView() override;
 private:
   Responder * tabController() const override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   constexpr static int k_totalNumberOfRows = 13;
   constexpr static int k_maxNumberOfDisplayableRows = 11;
   static constexpr KDCoordinate k_cellHeight = 20;

apps/statistics/histogram_parameter_controller.cpp

@@ -30,15 +30,6 @@ void HistogramParameterController::willDisplayCellForIndex(HighlightCell * cell,
   FloatParameterController::willDisplayCellForIndex(cell, index);
 }
 
-void HistogramParameterController::unloadView() {
-  for (int i = 0; i < k_numberOfCells; i++) {
-    assert(m_cells[i] != nullptr);
-    delete m_cells[i];
-    m_cells[i] = nullptr;
-  }
-  FloatParameterController::unloadView();
-}
-
 float HistogramParameterController::parameterAtIndex(int index) {
   assert(index >= 0 && index < k_numberOfCells);
   if (index == 0) {
@@ -76,14 +67,21 @@ int HistogramParameterController::reusableParameterCellCount(int type) {
   return k_numberOfCells;
 }
 
-View * HistogramParameterController::createView() {
-  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::createView();
+View * HistogramParameterController::loadView() {
+  SelectableTableView * tableView = (SelectableTableView *)FloatParameterController::loadView();
   for (int i = 0; i < k_numberOfCells; i++) {
-    assert(m_cells[i] == nullptr);
     m_cells[i] = new MessageTableCellWithEditableText(tableView, this, m_draftTextBuffer, I18n::Message::Default);
   }
   return tableView;
 }
 
+void HistogramParameterController::unloadView(View * view) {
+  for (int i = 0; i < k_numberOfCells; i++) {
+    delete m_cells[i];
+    m_cells[i] = nullptr;
+  }
+  FloatParameterController::unloadView(view);
+}
+
 }
 

apps/statistics/histogram_parameter_controller.h

@@ -13,13 +13,13 @@ public:
   const char * title() override;
   int numberOfRows() override;
   void willDisplayCellForIndex(HighlightCell * cell, int index) override;
-  void unloadView() override;
 private:
   HighlightCell * reusableParameterCell(int index, int type) override;
   int reusableParameterCellCount(int type) override;
   float parameterAtIndex(int index) override;
   bool setParameterAtIndex(int parameterIndex, float f) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   char m_draftTextBuffer[MessageTableCellWithEditableText::k_bufferLength];
   constexpr static int k_numberOfCells = 2;
   MessageTableCellWithEditableText * m_cells[k_numberOfCells];

apps/statistics/store_controller.cpp

@@ -26,15 +26,6 @@ void StoreController::willDisplayCellAtLocation(HighlightCell * cell, int i, int
   mytitleCell->setMessage(I18n::Message::Sizes);
 }
 
-void StoreController::unloadView() {
-  for (int i = 0; i < k_numberOfTitleCells; i++) {
-    assert(m_titleCells[i] != nullptr);
-    delete m_titleCells[i];
-    m_titleCells[i] = nullptr;
-  }
-  Shared::StoreController::unloadView();
-}
-
 HighlightCell * StoreController::titleCells(int index) {
   assert(index >= 0 && index < k_numberOfTitleCells);
   return m_titleCells[index];
@@ -51,12 +42,19 @@ bool StoreController::setDataAtLocation(float floatBody, int columnIndex, int ro
   return Shared::StoreController::setDataAtLocation(floatBody, columnIndex, rowIndex);
 }
 
-View * StoreController::createView() {
+View * StoreController::loadView() {
   for (int i = 0; i < k_numberOfTitleCells; i++) {
-    assert(m_titleCells[i] == nullptr);
     m_titleCells[i] = new EvenOddMessageTextCell(KDText::FontSize::Small);
   }
-  return Shared::StoreController::createView();
+  return Shared::StoreController::loadView();
+}
+
+void StoreController::unloadView(View * view) {
+  for (int i = 0; i < k_numberOfTitleCells; i++) {
+    delete m_titleCells[i];
+    m_titleCells[i] = nullptr;
+  }
+  Shared::StoreController::unloadView(view);
 }
 
 }

apps/statistics/store_controller.h

@@ -11,11 +11,11 @@ class StoreController : public Shared::StoreController {
 public:
   StoreController(Responder * parentResponder, Store * store, ButtonRowController * header);
   void willDisplayCellAtLocation(HighlightCell * cell, int i, int j) override;
-  void unloadView() override;
 private:
   bool setDataAtLocation(float floatBody, int columnIndex, int rowIndex) override;
   HighlightCell * titleCells(int index) override;
-  View * createView() override;
+  View * loadView() override;
+  void unloadView(View * view) override;
   EvenOddMessageTextCell * m_titleCells[k_numberOfTitleCells];
 };
 

apps/variable_box_controller.cpp

@@ -264,5 +264,6 @@ void VariableBoxController::viewWillAppear() {
 }
 
 void VariableBoxController::viewDidDisappear() {
+  StackViewController::viewDidDisappear();
   m_contentViewController.deselectTable();
 }

escher/include/escher/alternate_empty_view_controller.h

@@ -15,8 +15,6 @@ public:
   void didBecomeFirstResponder() override;
   void viewWillAppear() override;
   void viewDidDisappear() override;
-  void loadView() override;
-  void unloadView() override;
 private:
   class ContentView : public View {
   public:

escher/include/escher/button_row_controller.h

@@ -28,8 +28,6 @@ public:
   bool setSelectedButton(int selectedButton);
   void viewWillAppear() override;
   void viewDidDisappear() override;
-  void loadView() override;
-  void unloadView() override;
 private:
   class ContentView : public View {
   public:
@@ -66,10 +64,6 @@ public:
   virtual Button * buttonAtIndex(int index, ButtonRowController::Position position) const;
   ButtonRowController * header();
   ButtonRowController * footer();
-  /* By default these two functions do not load anything. They should be
-   * overrided if the delegate dynamically allocate the button views. */
-  virtual void loadButtonView();
-  virtual void unloadButtonView();
 private:
   ButtonRowController * m_header;
   ButtonRowController * m_footer;

escher/include/escher/dynamic_view_controller.h

@@ -15,10 +15,13 @@ public:
   DynamicViewController(Responder * parentResponder);
   ~DynamicViewController();
   View * view() override;
-  virtual void loadView() override;
-  virtual void unloadView() override;
+  void viewWillAppear() override;
+  void viewDidDisappear() override;
 private:
-  virtual View * createView() = 0;
+  void loadViewIfNeeded();
+  void unloadViewIfNeeded();
+  virtual View * loadView() = 0;
+  virtual void unloadView(View * view) = 0;
   View * m_view;
 };
 

escher/include/escher/modal_view_controller.h

@@ -17,8 +17,6 @@ public:
   bool isDisplayingModal();
   void viewWillAppear() override;
   void viewDidDisappear() override;
-  void loadView() override;
-  void unloadView() override;
 private:
   class ContentView : public View {
   public:

escher/include/escher/stack_view_controller.h

@@ -23,8 +23,6 @@ public:
   void didBecomeFirstResponder() override;
   void viewWillAppear() override;
   void viewDidDisappear() override;
-  void loadView() override;
-  void unloadView() override;
 private:
   class Frame {
   public:

escher/include/escher/tab_view_controller.h

@@ -20,8 +20,6 @@ public:
   void willResignFirstResponder() override;
   void viewWillAppear() override;
   void viewDidDisappear() override;
-  void loadView() override;
-  void unloadView() override;
 private:
   ViewController * activeViewController();
   class ContentView : public View {

escher/include/escher/view_controller.h

@@ -32,8 +32,6 @@ public:
   ViewController(Responder * parentResponder);
   virtual const char * title();
   virtual View * view() = 0;
-  virtual void loadView();
-  virtual void unloadView();
   virtual void viewWillAppear();
   virtual void viewDidDisappear();
 };

escher/src/alternate_empty_view_controller.cpp

@@ -86,15 +86,3 @@ void AlternateEmptyViewController::viewDidDisappear() {
     m_contentView.mainViewController()->viewDidDisappear();
   }
 }
-
-void AlternateEmptyViewController::loadView() {
-  if (!m_contentView.alternateEmptyViewDelegate()->isEmpty()) {
-    m_contentView.mainViewController()->loadView();
-  }
-}
-
-void AlternateEmptyViewController::unloadView() {
-  if (!m_contentView.alternateEmptyViewDelegate()->isEmpty()) {
-    m_contentView.mainViewController()->unloadView();
-  }
-}

escher/src/app.cpp

@@ -91,11 +91,10 @@ const Container * App::container() const {
 }
 
 void App::didBecomeActive(Window * window) {
-  m_modalViewController.loadView();
   View * view = m_modalViewController.view();
   assert(m_modalViewController.app() == this);
-  window->setContentView(view);
   m_modalViewController.viewWillAppear();
+  window->setContentView(view);
   setFirstResponder(&m_modalViewController);
   window->redraw();
 }
@@ -106,5 +105,4 @@ void App::willBecomeInactive() {
   }
   setFirstResponder(nullptr);
   m_modalViewController.viewDidDisappear();
-  m_modalViewController.unloadView();
 }

escher/src/button_row_controller.cpp

@@ -26,12 +26,6 @@ ButtonRowController * ButtonRowDelegate::header() {
   return m_header;
 }
 
-void ButtonRowDelegate::loadButtonView() {
-}
-
-void ButtonRowDelegate::unloadButtonView() {
-}
-
 ButtonRowController::ContentView::ContentView(ViewController * mainViewController, ButtonRowDelegate * delegate, Position position, Style style) :
   View(),
   m_mainViewController(mainViewController),
@@ -230,21 +224,10 @@ bool ButtonRowController::handleEvent(Ion::Events::Event event) {
 void ButtonRowController::viewWillAppear() {
   /* We need to layout subviews at first appearance because the number of
    * buttons might have changed between 2 appearences. */
-  m_contentView.mainViewController()->viewWillAppear();
   m_contentView.layoutSubviews();
+  m_contentView.mainViewController()->viewWillAppear();
 }
 
 void ButtonRowController::viewDidDisappear() {
   m_contentView.mainViewController()->viewDidDisappear();
-}
-
-void ButtonRowController::loadView() {
-  m_contentView.buttonRowDelegate()->loadButtonView();
-  m_contentView.mainViewController()->loadView();
-  m_contentView.layoutSubviews();
-}
-
-void ButtonRowController::unloadView() {
-  m_contentView.buttonRowDelegate()->unloadButtonView();
-  m_contentView.mainViewController()->unloadView();
-}
+}

escher/src/dynamic_view_controller.cpp

@@ -9,24 +9,32 @@ DynamicViewController::DynamicViewController(Responder * parentResponder) :
 }
 
 DynamicViewController::~DynamicViewController() {
-  if (m_view) {
-    delete m_view;
-    m_view = nullptr;
-  }
+  assert(m_view == nullptr);
 }
 
 View * DynamicViewController::view() {
-  assert(m_view != nullptr);
+  loadViewIfNeeded();
   return m_view;
 }
 
-void DynamicViewController::loadView() {
-  assert(m_view == nullptr);
-  m_view = createView();
+void DynamicViewController::viewWillAppear() {
+  loadViewIfNeeded();
 }
 
-void DynamicViewController::unloadView() {
-  assert(m_view != nullptr);
-  delete m_view;
-  m_view = nullptr;
+void DynamicViewController::viewDidDisappear() {
+  unloadViewIfNeeded();
+}
+
+void DynamicViewController::loadViewIfNeeded() {
+  if (m_view == nullptr) {
+    m_view = loadView();
+    assert(m_view != nullptr);
+  }
+}
+
+void DynamicViewController::unloadViewIfNeeded() {
+  if (m_view != nullptr) {
+    unloadView(m_view);
+    m_view = nullptr;
+  }
 }

escher/src/modal_view_controller.cpp

@@ -57,8 +57,10 @@ KDRect ModalViewController::ContentView::frame() {
 }
 
 void ModalViewController::ContentView::layoutSubviews() {
+  assert(m_regularView != nullptr);
   m_regularView->setFrame(bounds());
   if (numberOfSubviews() == 2) {
+  assert(m_currentModalView != nullptr);
     m_currentModalView->setFrame(frame());
   }
 }
@@ -110,8 +112,6 @@ void ModalViewController::displayModalViewController(ViewController * vc, float
   m_currentModalViewController = vc;
   vc->setParentResponder(this);
   m_previousResponder = app()->firstResponder();
-  m_regularViewController->viewDidDisappear();
-  vc->loadView();
   m_contentView.presentModalView(vc->view(), verticalAlignment, horizontalAlignment, topMargin, leftMargin, bottomMargin, rightMargin);
   m_currentModalViewController->viewWillAppear();
   app()->setFirstResponder(vc);
@@ -119,10 +119,8 @@ void ModalViewController::displayModalViewController(ViewController * vc, float
 
 void ModalViewController::dismissModalViewController() {
   m_currentModalViewController->viewDidDisappear();
-  m_regularViewController->viewWillAppear();
   app()->setFirstResponder(m_previousResponder);
   m_contentView.dismissModalView();
-  m_currentModalViewController->unloadView();
   m_currentModalViewController = nullptr;
 }
 
@@ -145,6 +143,8 @@ bool ModalViewController::handleEvent(Ion::Events::Event event) {
 }
 
 void ModalViewController::viewWillAppear() {
+  m_contentView.setMainView(m_regularViewController->view());
+  m_contentView.layoutSubviews();
   if (m_contentView.isDisplayingModal()) {
     m_currentModalViewController->viewWillAppear();
   }
@@ -157,19 +157,3 @@ void ModalViewController::viewDidDisappear() {
   }
   m_regularViewController->viewDidDisappear();
 }
-
-void ModalViewController::loadView() {
-  if (m_contentView.isDisplayingModal()) {
-    m_currentModalViewController->loadView();
-  }
-  m_regularViewController->loadView();
-  m_contentView.setMainView(m_regularViewController->view());
-  m_contentView.layoutSubviews();
-}
-
-void ModalViewController::unloadView() {
-  if (m_contentView.isDisplayingModal()) {
-    m_currentModalViewController->unloadView();
-  }
-  m_regularViewController->unloadView();
-}

escher/src/stack_view_controller.cpp

@@ -89,7 +89,6 @@ void StackViewController::push(ViewController * vc, KDColor textColor, KDColor b
   setupActiveViewController();
   if (m_numberOfChildren > 1) {
     m_childrenFrame[m_numberOfChildren-2].viewController()->viewDidDisappear();
-    m_childrenFrame[m_numberOfChildren-2].viewController()->unloadView();
   }
 }
 
@@ -98,10 +97,9 @@ void StackViewController::pop() {
   assert(m_numberOfChildren > 0);
   ViewController * vc = m_childrenFrame[m_numberOfChildren-1].viewController();
   m_numberOfChildren--;
-  vc->viewDidDisappear();
   setupActiveViewController();
   vc->setParentResponder(nullptr);
-  vc->unloadView();
+  vc->viewDidDisappear();
 }
 
 void StackViewController::pushModel(Frame frame) {
@@ -111,7 +109,6 @@ void StackViewController::pushModel(Frame frame) {
 void StackViewController::setupActiveViewController() {
   ViewController * vc = m_childrenFrame[m_numberOfChildren-1].viewController();
   vc->setParentResponder(this);
-  vc->loadView();
   m_view.setContentView(vc->view());
   vc->viewWillAppear();
   vc->setParentResponder(this);
@@ -136,8 +133,14 @@ View * StackViewController::view() {
 }
 
 void StackViewController::viewWillAppear() {
+  /* Load the stack view */
+  for (int i = 0; i < m_numberOfChildren; i++) {
+    m_view.pushStack(m_childrenFrame[i]);
+  }
+  /* Load the visible controller view */
   ViewController * vc = m_childrenFrame[m_numberOfChildren-1].viewController();
   if (m_numberOfChildren > 0 && vc) {
+    m_view.setContentView(vc->view());
     vc->viewWillAppear();
   }
 }
@@ -147,27 +150,7 @@ void StackViewController::viewDidDisappear() {
   if (m_numberOfChildren > 0 && vc) {
     vc->viewDidDisappear();
   }
-}
-
-void StackViewController::loadView() {
-  /* Load the stack view */
-  for (int i = 0; i < m_numberOfChildren; i++) {
-    m_view.pushStack(m_childrenFrame[i]);
-  }
-  /* Load the visible controller view */
-  ViewController * vc = m_childrenFrame[m_numberOfChildren-1].viewController();
-  if (m_numberOfChildren > 0 && vc) {
-    vc->loadView();
-    m_view.setContentView(vc->view());
-  }
-}
-
-void StackViewController::unloadView() {
   for (int i = 0; i < m_numberOfChildren; i++) {
     m_view.popStack();
   }
-  ViewController * vc = m_childrenFrame[m_numberOfChildren-1].viewController();
-  if (m_numberOfChildren > 0 && vc) {
-    vc->unloadView();
-  }
 }

escher/src/tab_view_controller.cpp

@@ -114,19 +114,15 @@ void TabViewController::setActiveTab(int8_t i, bool forceReactive) {
   ViewController * activeVC = m_children[i];
   if (i  != m_activeChildIndex || forceReactive) {
     if (i != m_activeChildIndex) {
-      activeVC->loadView();
       m_view.setActiveView(activeVC->view());
-    }
-    m_view.m_tabView.setActiveIndex(i);
-    if (i >= 0) {
       m_children[i]->viewWillAppear();
     }
+    m_view.m_tabView.setActiveIndex(i);
   }
   app()->setFirstResponder(activeVC);
   if (i  != m_activeChildIndex || forceReactive) {
       if (m_activeChildIndex >= 0 && m_activeChildIndex != i) {
       m_children[m_activeChildIndex]->viewDidDisappear();
-      m_children[m_activeChildIndex]->unloadView();
     }
     m_activeChildIndex = i;
   }
@@ -166,15 +162,6 @@ const char * TabViewController::tabName(uint8_t index) {
 }
 
 void TabViewController::viewWillAppear() {
-  activeViewController()->viewWillAppear();
-  m_view.m_tabView.setActiveIndex(m_activeChildIndex);
-}
-
-void TabViewController::viewDidDisappear() {
-  activeViewController()->viewDidDisappear();
-}
-
-void TabViewController::loadView() {
   if (m_view.m_tabView.numberOfTabs() != m_numberOfChildren) {
     for (int i=0; i<m_numberOfChildren; i++) {
       m_view.m_tabView.addTab(m_children[i]);
@@ -183,12 +170,13 @@ void TabViewController::loadView() {
   if (m_activeChildIndex < 0) {
     m_activeChildIndex = 0;
   }
-  m_children[m_activeChildIndex]->loadView();
   m_view.setActiveView(m_children[m_activeChildIndex]->view());
+  activeViewController()->viewWillAppear();
+  m_view.m_tabView.setActiveIndex(m_activeChildIndex);
 }
 
-void TabViewController::unloadView() {
-  activeViewController()->unloadView();
+void TabViewController::viewDidDisappear() {
+  activeViewController()->viewDidDisappear();
 }
 
 ViewController * TabViewController::activeViewController() {

escher/src/view_controller.cpp

@@ -15,8 +15,3 @@ void ViewController::viewWillAppear() {
 void ViewController::viewDidDisappear() {
 }
 
-void ViewController::loadView() {
-}
-
-void ViewController::unloadView() {
-}