When you have 2 screens in a stack with the bottom one with gestureEnabled=false using the back gesture causes the screen to become unresponsive. This seems to be caused by setting interactivePopGestureRecognizer.enabled = NO as soon as the gesture starts. This causes the gesture to cancel immediately and leaves the screen in an unresponsive state.
<Stack><Screen gestureEnabled={false} /><Screen /></Stack>
To fix this instead of using interactivePopGestureRecognizer.enabled we can leverage the existing delegate that we have in RNScreenStack. In gestureRecognizerShouldBegin we can check if the top screen has gestures enabled.
To make this simpler I moved the gestureEnabled config to Screen instead of HeaderConfig. I think it also makes more sense conceptually since the gesture is tied to the screen and not the header. It also simplifies the android code a bit.
This is a breaking change.
Update
This now only moves the config to screen since a separate fix was merged for the bug.
Appear event is used by react-navigation to properly dispatch focus. It is important that appear is dispatched after dismissed event. The reverse order of actions would result in getting react-navigation stack in a weird state.
It is relatively streightforward to implement onAppear event on iOS where we hook into didAppear callback from UIViewController. It gets dispatched in the right moment, that is when the transition is fully over.
On Android however it is much more tricky. There is no standard way to be notified from the fragment level that fragment transition finished. One way that is frequently recommended is to override Fragment.onCreateAnimation. However, this only works when custom transitions are provided (e.g. if we set the transition to use fade animation). As we want the platform native transition to be run by default we had to look for other ways. The current approach relies on fragment container's callbacks startViewTransition and endViewTransition, with the latter being triggered once the animation is over. We also need to take into account that a good starting point for the transition is when we call commit on fragment transaction. We use these two methods to determine if the fragment is instantiated (onCreate) within a running transaction and if so we schedule event dispatch at the moment when endViewTransition is called.
Another change this commit introduces on the Android side is that we no longer rely on show/hide for replacing fragments on stack and we now use add/remove transaction methods. Due to this change we had to make our fragments reusable and make onCreateView indempotent.
A few bugs fixed with android native stack in this commit:
- fixed a problem with views not resizing when keyboard appears, the bug was due to onMeasure forwardin getHeight which was the old height of the container instead of the changed one
- fixed a problem with back button behavior not being consistent. Now back button is controlled by 'gestureEnabled' to emulate iOS behavior where there is no hw back button but you can swipe back instead.
- added compatibility for "contained" modal styles - for now we always render "containted" fragments on Android, plan to add a way to render in dialogs in the future
