rdar://20762442: MPMoviePlayerController crasher regression in iOS 8.4 beta 2

MPMoviePlayerController crasher regression in iOS 8.4 beta 2

Originator:	cedric.luthi
Number:	rdar://20762442	Date Originated:	30-Apr-2015 02:56 PM
Status:	Open	Resolved:
Product:	iOS SDK	Product Version:	8.4 (12H4086d)
Classification:	Crash/Hang/Data Loss	Reproducible:	Always

 
Summary:
Using a MPMoviePlayerController, it is possible to change the currently playing movie by changing its `contentURL` property. Changing the URL then playing the movie should work fine. This behavior is broken in the latest iOS 8.4 beta.

Steps to Reproduce:
1. Run the attached sample project (KVO externalPlaybackActive crash)
2. Tap the "Play Basic Stream" button
3. Tap the "Play Advanced Stream" button
4. Observer the app crashing

Expected Results:
There should be no crash and the app should play the advanced stream.

Actual Results:
The app crashes with the following exception:
*** Terminating app due to uncaught exception 'NSRangeException', reason: 'Cannot remove an observer <MPAVController 0x146503c70> for the key path "externalPlaybackActive" from <MPQueuePlayer 0x170106390> because it is not registered as an observer.'

Version:
iOS 8.4 (12H4086d)

Notes:
Changing the content URL of a movie player controller worked fine since iOS 2.0. This regression was introduced in iOS 8.4. The sample project works fine on iOS 8.3 and earlier.

Configuration:
iPad Air 64GB A1474

Note to Open Radar users:
The "KVO externalPlaybackActive crash" sample project is available at https://github.com/0xced/radars/tree/master/KVO%20externalPlaybackActive%20crash

Comments

Cédric Luthi

This crash is not fixed in iOS 8.4 beta 3 (Build: 12H4098c).

By cedric.luthi at May 12, 2015, 7:47 a.m. (reply...)

Apple Developer Relations

Please verify this issue with iOS 8.4 beta 3 (Build: 12H4098c) and update your bug report at http://bugreport.apple.com/ with your results.

iOS 8.4 beta 3 (Build: 12H4098c) https://developer.apple.com/devcenter/ios/index.action Posted: May 11, 2015

If this issue still occurs, please update your bug report with relevant logs.

Logging Instructions/Test Case Requirements: https://developer.apple.com/bug-reporting/ios/

By cedric.luthi at May 12, 2015, 7:45 a.m. (reply...)

Easy workaround

It turns out there is a pretty easy workaround: just call the stop method before changing the content URL.

See https://github.com/0xced/radars/blob/6c36f5a76ce856d152df6d6ace13411a662cef21/KVO%20externalPlaybackActive%20crash/KVO%20externalPlaybackActive%20crash/ViewController.m#L37-L40

By cedric.luthi at April 30, 2015, 6:04 p.m. (reply...)

Still reproducible with suggested workaround

Even calling to stop before changing contentURL does not help. But really after mentioned workaround it is reproducible rarely.

I could fix it by executing play asynchronously

playerController.contentURL = URL

dispatch_async(dispatch_get_main_queue()) {

playerController.play()

}

By igor.palaguta at July 2, 2015, 12:38 p.m. (reply...)

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