I would like to detect when flutter app comes back from background.
In other SDKs for crossApp development, there is usually a listener when app changes this state.
Is there anything similar in flutter?
class _AppState extends State<App> with WidgetsBindingObserver {
#override
void initState() {
super.initState();
//add an observer to monitor the widget lyfecycle changes
WidgetsBinding.instance!.addObserver(this);
}
#override
void dispose() {
//don't forget to dispose of it when not needed anymore
WidgetsBinding.instance!.removeObserver(this);
super.dispose();
}
late AppLifecycleState _lastState;
#override
void didChangeAppLifecycleState(AppLifecycleState state) {
super.didChangeAppLifecycleState(state);
if (state == AppLifecycleState.resumed && _lastState == AppLifecycleState.paused) {
//now you know that your app went to the background and is back to the foreground
}
_lastState = state; //register the last state. When you get "paused" it means the app went to the background.
}
}
Related
Say I have a late TextEditingController. It's initially constructed somewhere
#override
void initState() {
super.initState();
controller = TextEditingController();
}
....
// then somewhere else I reconstruct it
// controller.dispose() // is this needed before the reassignment?
controller = TextEditingController();
Thanks!
No Before initialise no need to dispose. But Yes, its good practice that when TextEditingControlleris no longer needed you need to dispose it.So you can dispose your all TextEditingControllers in dispose method.
void dispose() {
controller.dispose(); //textFiledName
super.dispose();
}
So dispose method triggered whenever the created object from the stateful widget is removed permanently from the widget tree, so Dispose releases allocated memory.
More details checkout this official link
TextField
dispose
I want to know what is the right way to dispose all text editing controllers in a list in flutter?
List<TextEditingController> controllers = [];
I tried this, but it's not working. What should be the correct approach for it?
dispose(){
for(TextEditingController controller in controllers){
controller.dispose();
}
}
You are trying to call dispose on your List<TextEditingController>and not on your TextEditingController. You need to change it inside your for loop body.
dispose() {
for(final TextEditingController controller in controllers){
controller.dispose();
}
}
You are calling on wrong variable:
#override
void dispose() {
for (TextEditingController controller in controllers) {
controller.dispose(); //<-- change this
}
super.dispose();
}
How can I listen to an overlay that is inserted in flutter?
I have a main screen which consists of a scroll view and a button which opens an overlay.
When the overlay is opened I want to disable scroll on the below scroll view.
Ive tried using RouteAware but it is only executed when pushing another PageRoute.
The listeners are only executed when I push a new route using the main navigator but ive found no solution on how to listen when an overlay is pushed ontop of the current route.
Code:
class MyWidget extends StatelessWidget {
#override
_MyWidget State createState() => _MyWidget State();
}
class _MyWidgetState extends StatefulWidget<MyWidget> with RouteAware {
bool _scrollDisabled = false;
#override
didChangeDependencies() {
super.didChangeDependencies();
getIt<RouteObserver>().subscribe(this, ModalRoute.of(context) as PageRoute);
}
#override
dispose() {
getIt<RouteObserver>().unsubscribe(this);
super.dispose();
}
didPushNext() {
print("didPushNext");
setState(() {
_scrollDisabled = true;
});
}
didPush() {
print("didPush");
}
}
what we can more do to avoid memory leak exception
#override
void dispose() {
customerNameController.dispose();
timer.cancel();
super.dispose();
}
How to show alert on screen when app is in background in flutter
or how to change state of flutter app from pause to resume
hi the answer is to use WidgetsBindingObserver.
in your app just add
class _MyScreenState extends State<MyScreen> with WidgetsBindingObserver{}
add the following inside our initState:
WidgetsBinding.instance.addObserver(this);
didChangeAppLifecycleState will be:
#override
void didChangeAppLifecycleState(AppLifecycleState state) {
super.didChangeAppLifecycleState(state);
if (state == AppLifecycleState.paused) {
// went to Background
}
if (state == AppLifecycleState.resumed) {
// came back to Foreground
}
}
here is the link of the full article link
I hope it will help you.