[apps] Use viewWillAppear to reload view after preference change

Change-Id: I4fba6bd6d4dee03e86ac5087dbc20ef4d7dd032b

apps/shared/interactive_curve_view_controller.h

@@ -27,6 +27,8 @@ public:
   Button * buttonAtIndex(int index) override;
 
   Responder * defaultController() override;
+
+  void viewWillAppear() override;
 protected:
   constexpr static float k_numberOfCursorStepsInGradUnit = 5.0f;
   virtual BannerView * bannerView() = 0;
@@ -55,7 +57,6 @@ private:
   Button m_rangeButton;
   Button m_zoomButton;
   Button m_defaultInitialisationButton;
-  Poincare::Expression::FloatDisplayMode m_displayModeVersion;
 };
 
 }