Recently, I’ve been getting intermittent error reports from my app claiming “unrecognized selector” in areas that could not possibly cause them, and yet they do.
For example, this one:
Error: NSInvalidArgumentException: *** -[NSCFString didReceiveMemoryWarning]: unrecognized selector sent to instance 0x541fe0
0 CoreFoundation 0x32de1e23 __handleUncaughtException + 230
1 libobjc.A.dylib 0x3266d894 _objc_terminate + 156
2 libstdc++.6.dylib 0x338c3a8c _ZN10__cxxabiv111__terminateEPFvvE + 84
3 libstdc++.6.dylib 0x338c3b04 _ZSt9terminatev + 24
4 libstdc++.6.dylib 0x338c3c2c __cxa_throw + 108
5 libobjc.A.dylib 0x3266be5c objc_exception_throw + 112
6 CoreFoundation 0x32de2bfd -[NSObject doesNotRecognizeSelector:] + 112
7 CoreFoundation 0x32d67b19 ___forwarding___ + 480
8 CoreFoundation 0x32d5e840 _CF_forwarding_prep_0 + 48
9 Foundation 0x33f765d9 _nsnote_callback + 184
10 CoreFoundation 0x32d9e511 _CFXNotificationPostNotification + 304
11 Foundation 0x33f741b3 -[NSNotificationCenter postNotificationName:object:userInfo:] + 70
12 Foundation 0x33f76519 -[NSNotificationCenter postNotificationName:object:] + 20
13 UIKit 0x30d18db8 -[UIApplication _performMemoryWarning] + 68
14 UIKit 0x30d18d50 -[UIApplication _receivedMemoryNotification] + 136
15 UIKit 0x30d18c80 _memoryStatusChanged + 64
16 CoreFoundation 0x32d66eb7 __CFNotificationCenterDarwinCallBack + 26
17 CoreFoundation 0x32d5cb51 __CFMachPortPerform + 78
18 CoreFoundation 0x32da452b CFRunLoopRunSpecific + 2302
19 CoreFoundation 0x32da3c1f CFRunLoopRunInMode + 50
20 GraphicsServices 0x31bb9374 GSEventRunModal + 196
21 UIKit 0x30bf3c30 -[UIApplication _run] + 560
22 UIKit 0x30bf2230 UIApplicationMain + 968
23 Mind 0x00002c68 main + 72
24 Mind 0x00002be4 start + 52
This is the OS sending a memory warning to my app, and somehow the application class has changed into a string.
It seems to happen a lot more when the code is invoked via an NSOperation:
Error: NSInvalidArgumentException: -[NSCFString setObject:forKey:]: unrecognized selector sent to instance 0x3e793088
9 Mind 0x0015de70 -[CCTextureCache textureFromFile:] + 528
10 Mind 0x0015d9f4 -[CCTextureCache loadImageUncached:pixelFormat:] + 116
11 Mind 0x0015d058 -[CCTextureCache addImage:pixelFormat:] + 152
12 Mind 0x00080524 -[ImageLoader imageWithFile:pixelFormat:] + 84
13 Mind 0x000854c4 -[ImageLoadOperation performLoad] + 68
14 Mind 0x00085800 -[ResourceLoadOperation main] + 112
15 Foundation 0x30c4c8b5 -[__NSOperationInternal start] + 664
16 Foundation 0x30c4c613 -[NSOperation start] + 22
17 Foundation 0x30cbdb63 ____startOperations_block_invoke_2 + 46
18 libSystem.B.dylib 0x31227858 _dispatch_call_block_and_release + 20
19 libSystem.B.dylib 0x3122863c _dispatch_worker_thread2 + 128
20 libSystem.B.dylib 0x311b1544 _pthread_wqthread + 400
21 libSystem.B.dylib 0x311a8b74 __stack_chk_fail + 4294967295
The code in question is:
[textures setObject:texture forKey:filename];
textures is type NSMutableDictionary* and never gets reassigned or deallocated (naturally, since this is a cache object). This is the only place where setObject is invoked in this method, yet according to the stack trace, textures was a string.
I also get this weirdness:
Error: NSInvalidArgumentException: -[NSConcreteNotification getPixelFormatForIdentifier:]: unrecognized selector sent to instance 0x5c021b0
9 Mind 0x0015dd0c -[CCTextureCache textureFromFile:] + 172
10 Mind 0x0015d9f4 -[CCTextureCache loadImageUncached:pixelFormat:] + 116
11 Mind 0x0015d058 -[CCTextureCache addImage:pixelFormat:] + 152
12 Mind 0x00080524 -[ImageLoader imageWithFile:pixelFormat:] + 84
13 Mind 0x000854c4 -[ImageLoadOperation performLoad] + 68
14 Mind 0x00085800 -[ResourceLoadOperation main] + 112
15 Foundation 0x347b78b5 -[__NSOperationInternal start] + 664
16 Foundation 0x347b7613 -[NSOperation start] + 22
17 Foundation 0x34828b63 ____startOperations_block_invoke_2 + 46
18 libSystem.B.dylib 0x32a2f858 _dispatch_call_block_and_release + 20
19 libSystem.B.dylib 0x32a3063c _dispatch_worker_thread2 + 128
20 libSystem.B.dylib 0x329b9544 _pthread_wqthread + 400
21 libSystem.B.dylib 0x329b0b74 __stack_chk_fail + 4294967295
This trace is from the following code in CCTextureCache:
CCTexture2DPixelFormat pixelFormat = [self getPixelFormatForIdentifier:identifier];
How CCTextureCache changed into NSConcreteNotification after having already called a number of methods on itself is baffling to say the least.
Has anyone else noticed this sort of thing? Am I somehow getting memory corruption?
Did you check some race conditions about multi-threads ? It seems like some resource freed by another thread, and current thread send a messaged to a deallocated object.