iOS Question Back key event

Search in the forum for TopLeftButtons. The shortcut way for the back button is that you HideBackButton in the Page and create a BarButton which you add in TopLeftButtons and handle this button's click event to go back (f.e. previouspage.Show). For home button I do not have a clue.

You cannot catch the home button. You can handle the Application_Background event.

The Page_Appear event can also be useful (it will fire after the back button is clicked).