willPop method Null safety
override
Returns RoutePopDisposition.doNotPop if any of callbacks added with addScopedWillPopCallback returns either false or null. If they all return true, the base Route.willPop's result will be returned. The callbacks will be called in the order they were added, and will only be called if all previous callbacks returned true.
Typically this method is not overridden because applications usually
don't create modal routes directly, they use higher level primitives
like showDialog. The scoped WillPopCallback list makes it possible
for ModalRoute descendants to collectively define the value of willPop.
See also:
- Form, which provides an
onWillPopcallback that uses this mechanism. - addScopedWillPopCallback, which adds a callback to the list this method checks.
- removeScopedWillPopCallback, which removes a callback from the list this method checks.
Implementation
@override
Future<RoutePopDisposition> willPop() async {
final _ModalScopeState<T>? scope = _scopeKey.currentState;
assert(scope != null);
for (final WillPopCallback callback in List<WillPopCallback>.of(_willPopCallbacks)) {
if (await callback() != true) {
return RoutePopDisposition.doNotPop;
}
}
return super.willPop();
}