Xamarin Shell - 硬件后退按钮

Question

I am testing https://github.com/xamarin/xamarin-forms-samples/tree/master/UserInterface/Xaminals application on android 9.

I would like to know why the hardware back button does not work as expected (return to the previous view)

Example:

1. Start app 2- Entered the Dogs tab
2. Press hardware back button
3. The application is suspended. You should go back to the cat list.

Example 2:

1. Start app
2. Entered the side menu and going to monkeys.
3. Press hardware back button
4. The application is suspended. You should go back to the cat list.

I'm not understanding why the hardware button only works correctly for example when I enter the detail of a cat and then I go back.

Answer 1

Android hardware back button by default closes the currently opened activity and activates an activity from the navigation stack. If you want to override this behavior, you need to handle the back button press and implement the navigation you need for your use case. Shell has this handy feature implemented with BackButtonBehavior property:

https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/shell/navigation#back-button-behavior

Answer 2

I would like to know why the hardware back button does not work as expected (return to the previous view) I'm not understanding why the hardware button only works correctly for example when I enter the detail of a cat and then I go back.

As I know, when a route from the Shell visual hierarchy is navigated to, a navigation stack isn't created. However, when a page that's not in the Shell visual hierarchy is navigated to, a navigation stack is created.

That's way the hardware back button does not work as you excepted.