[AVPlaybackItem fpItem]: message sent to deallocated instance

问题

I play a movie with MPMoviePlayerController. Later, the app is "restarted" (meaning a pseudo-reset, where all viewControllers are removed and the user returns to the home screen), and the same movie is played again.

This leads to a crash in iOS 3.2.2 on the iPad:

[AVPlaybackItem fpItem]: message sent to deallocated instance

I have no idea where that comes from. Seems to be something private. Has anyone experienced and possibly solved the same problem?

The stack trace for that particular address:

(gdb) info malloc 0x11471400
Alloc: Block address: 0x11471400 length: 76
Stack - pthread: 0xa0630500 number of frames: 34
    0: 0x9534e0c3 in malloc_zone_calloc
    1: 0x9534e01a in calloc
    2: 0x343edc9 in _internal_class_createInstanceFromZone
    3: 0x344b5c9 in _class_createInstanceFromZone
    4: 0x344b5ef in class_createInstance
    5: 0x3326b57 in +[NSObject allocWithZone:]
    6: 0x332583a in +[NSObject alloc]
    7: 0x536ab67 in -[AVPlaybackQueue queueItemWasAddedNotification:]
    8: 0x27f586 in _nsnote_callback
    9: 0x328d165 in _CFXNotificationPostNotification
   10: 0x2762ca in -[NSNotificationCenter postNotificationName:object:userInfo:]
   11: 0x5354982 in -[AVQueue itemWasAdded:atIndex:]
   12: 0x5354801 in -[AVQueue insertItem:atIndex:error:]
   13: 0x53549d8 in -[AVQueue appendItem:error:]
   14: 0x535c3be in -[AVController addNextFeederItemToQueue]
   15: 0x535b06f in -[AVController checkQueueSpace]
   16: 0x5359f46 in -[AVController setQueue:]
   17: 0x535ac62 in -[AVController setQueueFeeder:withIndex:]
   18: 0x30eee20 in -[MPAVController reloadFeederWithStartIndex:]
   19: 0x30deed7 in -[MPMoviePlayerControllerNew _prepareToPlayWithStartIndex:]
   20: 0x30dc686 in -[MPMoviePlayerControllerNew prepareToPlay]
   21: 0x27f586 in _nsnote_callback
   22: 0x328d165 in _CFXNotificationPostNotification
   23: 0x2762ca in -[NSNotificationCenter postNotificationName:object:userInfo:]
   24: 0x281238 in -[NSNotificationCenter postNotificationName:object:]
   25: 0x31596d1 in -[MPMovie _determineMediaType]
   26: 0x291b87 in __NSFireDelayedPerform
   27: 0x32747dc in CFRunLoopRunSpecific
   28: 0x32738a8 in CFRunLoopRunInMode
   29: 0x3aaf89d in GSEventRunModal
   30: 0x3aaf962 in GSEventRun
   31: 0x52b372 in UIApplicationMain
   32: 0x27be in main at /blablabla 
   33: 0x2735 in start

回答1:

It sounds like you're calling release more than you are calling retain.

Does the error message not contain a hex address at the end? If it does, follow these steps to hunt down the offending object:

Navigate to Project->Edit Active Executable (or press Command-Option-X). Choose the arguments tab. Set the environmental variables as shown below:
Run the program and repeat the steps needed to reproduce the error.
Copy the hex address at the end of the error. Then, in the debugger console type this command: (gdb) info malloc-history <paste-address-here>.
Examine the output to hunt down the offending object.

P.S. Don't forget to disable the environmental variables when you're done.

回答2:

maybe you call prepare to play more than once for the same movie and i think this is the problem and it exists to all ios prior to 4.3 i guess (not sure though) so just flag the movie if prepare to play was called once then don't recall it for the same file

来源：https://stackoverflow.com/questions/4206147/avplaybackitem-fpitem-message-sent-to-deallocated-instance

标签

iphone

cocoa-touch

ipad

crash

mpmovieplayercontroller