Steven Wexler Steven Wexler - 5 months ago 22
iOS Question

Listen for event when user opens app switcher on iOS

How can I listen for an event when a user opens the app switcher (the UI that comes up when a user double taps on the home button) on iOS.

I though UIApplicationDidEnterBackgroundNotification would fire, but it doesn't fire when I open the app switcher. It only fires when I minimize the app by tapping the home button once.

NSNotificationCenter.defaultCenter().addObserver(
self,
selector: "onPause",
name: UIApplicationDidEnterBackgroundNotification,
object:nil)

func onPause() {
//Not invoked when app switcher is opened
}

Answer

You should receive a UIApplicationWillResignActiveNotification in that case. Your app is no longer the active app, but has not yet moved to the background.

If the user goes back to your app you'll get a UIApplicationDidBecomeActiveNotification when the app becomes active again. If the user does swap to another app, or select the springboard, then you should get a UIApplicationDidEnterBackgroundNotification.

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