Migration guide for adding AppLifecycleState.hidden
Summary
#A new hidden
state was added to the AppLifecycleState
enum to denote
when the application is not visible.
Context
#The AppLifecycleState
enum is used to indicate which lifecycle state the
application is in when WidgetsBindingObserver.didChangeAppLifecycleState
is called.
Description of change
#The new state AppLifecycleState.hidden
was added to the AppLifecycleState
enum in the dart:ui
package.
The hidden
state is entered when all of the application views are no longer
visible to the user. On Android and iOS, this state is entered briefly whenever
the state machine traverses from inactive to paused, or from paused to inactive.
It doesn't change when paused or inactive are entered. On other platforms, it
will be in this state while the application is not visible.
Migration guide
#If code has switch statements that handle all cases of the AppLifecycleState
enum, a new case will need to be added to handle the AppLifecycleState.hidden
state.
Code before migration:
void didChangeAppLifecycleState(AppLifecycleState state) {
switch (state) {
case AppLifecycleState.resumed:
case AppLifecycleState.inactive:
// Do something when the app is visible...
break;
case AppLifecycleState.paused:
case AppLifecycleState.detached:
// Do something when the app is not visible...
break;
}
}
Code after migration:
void didChangeAppLifecycleState(AppLifecycleState state) {
switch (state) {
case AppLifecycleState.resumed:
case AppLifecycleState.inactive:
// Do something when the app is visible...
break;
case AppLifecycleState.hidden: // <-- This is the new state.
case AppLifecycleState.paused:
case AppLifecycleState.detached:
// Do something when the app is not visible...
break;
}
}
If there is already a default:
case in the switch statement, or the code uses
conditionals instead, then the code will compile without changes, but the
default case or conditional will still need to be evaluated to decide if the
hidden
state should also be handled.
Timeline
#Landed in version: 3.11.0-16.0.pre
In stable release: 3.13.0
References
#Relevant PRs:
- PR 42418: Adds
AppLifecycleState.hidden
enum value
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