[SOLVED] Detect application refocus event

Detect application refocus event

I need to know each time the user is starting to use the application.

Case 1 (OK) : The app is not started.

The user starts the application from scratch.

I add a listener on the app's bootstrap, and I am aware when it starts.

Case 2 (TODO) : The app has been started but it's not active anymore

The user reload the application from the taskbar.

I want to know when the application comes from the taskbar to the foreground (like a alt+tab).

This is tricky to catch, because the app is still running and I don't know which event to listen to. In fact, I don't even know how to name this behaviour.

Solution

An ios-app developper accepted to help me. His answer suits me very well, as it seem clean et reusable. So I will produce it here :

The "app come to foreground" event can be catched through the applicationWillEnterForeground event. Phonegap/Cordova allows to call javascript functions through the Cordova classes. The webView object has a dedicated method to launch js scripts.

So I opened the file Projet/Classes/Cordova/AppDelegate.m :

- (void)applicationWillEnterForeground:(UIApplication *)application {
    NSLog(@"applicationWillEnterForeground: %@", self.viewController.webView);
    [self.viewController.webView stringByEvaluatingJavaScriptFromString:@"notifyForegroundEvent();"];

}

And I added the notifyForegroundEvent() method somewhere in the root of my js files :

var notifyForegroundEvent = function() {
  console.log('notifyForegroundEvent()');
  // Do something here
}

Et voilà