iOS Extension - Detect "extension state changes" (Background/Foreground)

Question

I have a share extension implemented for iOS8. The service uses OAuth to authenticate. The login info I use for the extension is shared with the container app.

The problem is:

When I am in the extension, then app switch to the container app and logout, and then app switch back to the host app containing the extension - How do I detect that the extension has just re-appeared? The extension is relying on certain information to be present in the shared DB between the container app and the extension, however, that data is removed when the app logs out.

I have tried registering for various "app notifications" such as UIApplicationDidBecomeActiveNotification. However, as expected, these aren't called for extensions.

How can I detect when the state of the extension changes such that I can make my extension more robust when it reappears?

er0 · Answer 1 · 2014-10-20T04:17:47.483

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The viewDidAppear:animated: method of your main view controller class should be called every time you reenter your extension. When you are about to leave, viewWillDisappear:animated: should be called.

edited Oct 20 '14 at 04:17

answered Oct 20 '14 at 04:12

er0

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Unfortunately this doesn't work. These functions are not called in this particular case (with extensions). – Adam Zielinski Oct 24 '14 at 19:02

score 0 · Answer 2 · answered May 01 '15 at 14:16

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See

NSExtensionContext.h

iOS 8.2 added a number of notifications to use for extensions:

NSExtensionHostDidBecomeActiveNotification
NSExtensionHostDidEnterBackgroundNotification
NSExtensionHostWillEnterForegroundNotification
NSExtensionHostWillResignActiveNotification

answered May 01 '15 at 14:16

Martin-Gilles Lavoie

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And solution for iOS 8.0? – Paulius Vindzigelskis Jul 08 '16 at 12:23
None that we investigated. We've decided to target 8.2+ and leave it at that. – Martin-Gilles Lavoie Jul 09 '16 at 18:15
how do you actually use these? – coolcool1994 Sep 19 '20 at 18:12
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[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hostIsInForegroundNotification:) name:@"NSExtensionHostDidBecomeActiveNotification" object:nil]; doesn't trigger the selector in extension. This answer doesn't work. – coolcool1994 Sep 19 '20 at 18:46
What I'm noticing is that the active/foreground one's don't trigger the first time you bring the host into the foreground. But they do trigger the second, etc. times after you have accessed the sharing extension in the host. – Chris Prince Mar 21 '21 at 15:07

iOS Extension - Detect "extension state changes" (Background/Foreground)

2 Answers2