[escher] Create dynamic view controller

Change-Id: Ic8fe6d095666aa7af76c8d328b0bf83342a09453

escher/src/dynamic_view_controller.cpp

@@ -0,0 +1,32 @@
+#include <escher/dynamic_view_controller.h>
+#include <escher/app.h>
+#include <assert.h>
+
+DynamicViewController::DynamicViewController(Responder * parentResponder) :
+  ViewController(parentResponder),
+  m_view(nullptr)
+{
+}
+
+DynamicViewController::~DynamicViewController() {
+  if (m_view) {
+    delete m_view;
+    m_view = nullptr;
+  }
+}
+
+View * DynamicViewController::view() {
+  assert(m_view != nullptr);
+  return m_view;
+}
+
+void DynamicViewController::loadView() {
+  assert(m_view == nullptr);
+  m_view = createView();
+}
+
+void DynamicViewController::unloadView() {
+  assert(m_view != nullptr);
+  delete m_view;
+  m_view = nullptr;
+}