iOS: App crashes due to a dispatch_queue

I am trying to use this code: https://stackoverflow.com/a/14063081/1011125.

But on my iPhone 4 (iOS 7), this part let's the whole app crash:

dispatch_queue_t queue = dispatch_queue_create("cameraQueue", NULL);
[output setSampleBufferDelegate:self queue:queue];

What's wrong with this little snippet?

Crash Log

OS Version:          iOS 7.1 (11D169)
Report Version:      104

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0xe000000c
Triggered by Thread:  2

Thread 0:
0   libsystem_kernel.dylib          0x38e4da58 mach_msg_trap + 20
1   libsystem_kernel.dylib          0x38e4d854 mach_msg + 44
2   CoreFoundation                  0x2e0bb896 __CFRunLoopServiceMachPort + 150
3   CoreFoundation                  0x2e0ba002 __CFRunLoopRun + 850
4   CoreFoundation                  0x2e024f4a CFRunLoopRunSpecific + 518
5   CoreFoundation                  0x2e024d2e CFRunLoopRunInMode + 102
6   GraphicsServices                0x32f2965e GSEventRunModal + 134
7   UIKit                           0x30970168 UIApplicationMain + 1132
8   Lockr                           0x00048fa0 main (main.m:16)
9   libdyld.dylib                   0x38daaab4 start + 0

Thread 1:
0   libsystem_kernel.dylib          0x38e4d808 kevent64 + 24
1   libdispatch.dylib               0x38d99de8 _dispatch_mgr_invoke + 228
2   libdispatch.dylib               0x38d88f6e _dispatch_mgr_thread$VARIANT$up + 34

Thread 2 Crashed:
0   libobjc.A.dylib                 0x388a7626 objc_msgSend + 6
1   AVFoundation                    0x2d00dc16 __74-[AVCaptureVideoDataOutput _AVCaptureVideoDataOutput_VideoDataBecameReady]_block_invoke + 394
2   libdispatch.dylib               0x38d85830 _dispatch_call_block_and_release + 8
3   libdispatch.dylib               0x38d85de8 _dispatch_queue_drain$VARIANT$up + 440
4   libdispatch.dylib               0x38d86292 _dispatch_queue_invoke$VARIANT$up + 34
5   libdispatch.dylib               0x38d9888a _dispatch_root_queue_drain + 74
6   libdispatch.dylib               0x38d98b1c _dispatch_worker_thread2 + 52
7   libsystem_pthread.dylib         0x38ec7bd0 _pthread_wqthread + 296
8   libsystem_pthread.dylib         0x38ec7a94 start_wqthread + 4

Thread 3 name:  com.apple.coremedia.player.async
Thread 3:
0   libsystem_kernel.dylib          0x38e4daa8 semaphore_wait_trap + 8
1   libdispatch.dylib               0x38d98f74 _dispatch_semaphore_wait_slow + 172
2   MediaToolbox                    0x2f540ab4 fpa_AsyncMovieControlThread + 1752
3   CoreMedia                       0x2e6531e0 figThreadMain + 192
4   libsystem_pthread.dylib         0x38ec9916 _pthread_body + 138
5   libsystem_pthread.dylib         0x38ec9886 _pthread_start + 98
6   libsystem_pthread.dylib         0x38ec7aa0 thread_start + 4

Thread 2 crashed with ARM Thread State (32-bit):
    r0: 0x15dd6e60    r1: 0x30f39275      r2: 0x00000004      r3: 0x0000000d
    r4: 0x15e58e20    r5: 0x30f39275      r6: 0x38f6696c      r7: 0x02b93f3c
    r8: 0x30f74e46    r9: 0xe0000000     r10: 0x2d07cd11     r11: 0x398b7cf8
    ip: 0x38f3a8cc    sp: 0x02b93ef8      lr: 0x2d00dc1b      pc: 0x388a7626
  cpsr: 0x60000030