onChange method
- Function listener
//////////////////////////////////////////////// LISTENING TO DB CHANGES /// //////////////////////////////////////////////// Listens to contact database changes and executes callback function.
Because of limitations both on iOS and on Android (see https://www.grokkingandroid.com/use-contentobserver-to-listen-to-changes/) it's not possible to tell which kind of change happened and on which contacts. It only notifies something changed in the contacts database.
listener
must be a parameterless function.
The return value is a function (returning Future<void>) that cancels the subscription.
Implementation
/// Listens to contact database changes and executes callback function.
///
/// Because of limitations both on iOS and on Android (see
/// https://www.grokkingandroid.com/use-contentobserver-to-listen-to-changes/)
/// it's not possible to tell which kind of change happened and on which
/// contacts. It only notifies something changed in the contacts database.
///
/// [listener] must be a parameterless function.
///
/// The return value is a function (returning [Future<void>]) that cancels the
/// subscription.
static Future<void> Function() onChange(Function listener) {
var subscription =
_eventChannel.receiveBroadcastStream().listen((event) => listener());
return () => subscription.cancel();
}