title: Random Crash with CA::Layer::set_position
body: <p>I have a crashing bug in my app.</p>
  
  <p>It happens in the same place, but not all the time. I haven't found the problem.</p>
  
  <p>Here are two crash logs: </p>
  
  <blockquote>
  <pre><code>    Incident Identifier: EB73AE61-00FB-4282-8F1D-B8ECEC19E02D
  CrashReporter Key:   6f005b28e796b18f3ab2687bb364b2be1eb137cd
  Hardware Model:      iPhone5,2
  Path:            /var/mobile/Applications/BF2F1016-8C00-40A3-BB75-0933F53741F0/*******.app/******
  Version:         ??? (???)
  Code Type:       ARM (Native)
  Parent Process:  launchd [1]
  
  Exception Type:  EXC_CRASH (SIGABRT)
  Exception Codes: 0x0000000000000000, 0x0000000000000000
  Crashed Thread:  0
  
  Last Exception Backtrace:
  0   CoreFoundation                    0x312d13e2 __exceptionPreprocess + 158
  1   libobjc.A.dylib                   0x38fc295e objc_exception_throw + 26
  2   CoreFoundation                    0x312d1302 +[NSException raise:format:] + 102
  3   QuartzCore                        0x32e8e106 CA::Layer::set_position(CA::Vec2&lt;double&gt; const&amp;, bool) + 206
  4   QuartzCore                        0x32e8e02e -[CALayer setPosition:] + 46
  5   QuartzCore                        0x32e8dfc2 -[CALayer setFrame:] + 554
  6   UIKit                             0x330e1bd2 -[UIView(Geometry) setFrame:] + 230
  7   UIKit                             0x330e18fc -[UIImageView _setViewGeometry:forMetric:] + 180
  8   UIKit                             0x330e183a -[UIImageView setFrame:] + 42
  9   etapes                            0x0006de1c 0x5c000 + 73244
  10  UIKit                             0x33203136 -[UIScrollView _endPanWithEvent:] + 3694
  11  UIKit                             0x3321c520 -[UIScrollView handlePan:] + 120
  12  UIKit                             0x331fdc5c _UIGestureRecognizerSendActions + 124
  13  UIKit                             0x331c539c -[UIGestureRecognizer _updateGestureWithEvent:] + 388
  14  UIKit                             0x333b215e ___UIGestureRecognizerUpdate_block_invoke_0543 + 42
  15  UIKit                             0x330e987e _UIGestureRecognizerRemoveObjectsFromArrayAndApplyBlocks + 214
  16  UIKit                             0x330e82c8 _UIGestureRecognizerUpdate + 1160
  17  UIKit                             0x330f31e2 -[UIWindow _sendGesturesForEvent:] + 762
  18  UIKit                             0x330f2dae -[UIWindow sendEvent:] + 86
  19  UIKit                             0x330e08dc -[UIApplication sendEvent:] + 376
  20  UIKit                             0x330e01ea _UIApplicationHandleEvent + 6194
  21  GraphicsServices                  0x34df75f2 _PurpleEventCallback + 586
  22  GraphicsServices                  0x34df7222 PurpleEventCallback + 30
  23  CoreFoundation                    0x312a63e2 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 30
  24  CoreFoundation                    0x312a6386 __CFRunLoopDoSource1 + 134
  25  CoreFoundation                    0x312a520a __CFRunLoopRun + 1378
  26  CoreFoundation                    0x31218238 CFRunLoopRunSpecific + 352
  27  CoreFoundation                    0x312180c4 CFRunLoopRunInMode + 100
  28  GraphicsServices                  0x34df6336 GSEventRunModal + 70
  29  UIKit                             0x331342b4 UIApplicationMain + 1116
  30  etapes                            0x0005e15e 0x5c000 + 8542
  31  etapes                            0x0005e114 0x5c000 + 8468
  </code></pre>
  </blockquote>
  
  <p>//////////////////////////// SECOND CRASH LOG ///////////////////////////////////</p>
  
  <blockquote>
  <pre><code>Incident Identifier: 4FE03135-D442-4CEA-B230-8322647262EE
  CrashReporter Key:   6f005b28e796b18f3ab2687bb364b2be1eb137cd
  Hardware Model:      iPhone5,2
  Process:         etapes [2916]
  Path:            /var/mobile/Applications/BF2F1016-8C00-40A3-BB75-0933F53741F0/******.app/****
  Version:         ??? (???)
  Code Type:       ARM (Native)
  Parent Process:  launchd [1]
  
  Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
  Exception Codes: KERN_INVALID_ADDRESS at 0x00000064
  Crashed Thread:  0
  
  Thread 0 name:  Dispatch queue: com.apple.main-thread
  Thread 0 Crashed:
  0   UIKit                             0x33df7b06 -[UIView(CALayerDelegate) actionForLayer:forKey:] + 138
  1   QuartzCore                        0x33ba7786 -[CALayer actionForKey:] + 70
  2   QuartzCore                        0x33ba7732 _ZL12actionForKeyP7CALayerPN2CA11TransactionEP8NSString + 54
  3   QuartzCore                        0x33ba7626 CA::Layer::begin_change(CA::Transaction*, unsigned int, objc_object*&amp;) + 126
  4   QuartzCore                        0x33ba2322 CA::Layer::setter(unsigned int, _CAValueType, void const*) + 178
  5   QuartzCore                        0x33bce782 -[CALayer setBackgroundColor:] + 30
  6   UIKit                             0x33e0ef50 -[UIView(Internal) _setBackgroundCGColor:withSystemColorName:] + 1016
  7   etapes                            0x000fc8d2 0xdd000 + 129234
  8   etapes                            0x000f8c6a 0xdd000 + 113770
  9   CoreFoundation                    0x31fe9ad0 __invoking___ + 64
  10  CoreFoundation                    0x31f4128a -[NSInvocation invoke] + 286
  11  Foundation                        0x328eaf60 -[NSInvocationOperation main] + 108
  12  Foundation                        0x32874a84 -[__NSOperationInternal start] + 836
  13  Foundation                        0x328ecfe2 __block_global_6 + 98
  14  libdispatch.dylib                 0x3a0f1790 _dispatch_call_block_and_release + 8
  15  libdispatch.dylib                 0x3a0f15d8 _dispatch_client_callout + 20
  16  libdispatch.dylib                 0x3a0f4e40 _dispatch_main_queue_callback_4CF + 224
  17  CoreFoundation                    0x31fba1ac __CFRunLoopRun + 1284
  18  CoreFoundation                    0x31f2d238 CFRunLoopRunSpecific + 352
  19  CoreFoundation                    0x31f2d0c4 CFRunLoopRunInMode + 100
  20  GraphicsServices                  0x35b0b336 GSEventRunModal + 70
  21  UIKit                             0x33e492b4 UIApplicationMain + 1116
  22  etapes                            0x000df15e 0xdd000 + 8542
  23  etapes                            0x000df114 0xdd000 + 8468
  </code></pre>
  </blockquote>
  
  <p>If you want more details, I'm available!</p>
  
  <p>after research, here is the code that is the problem :</p>
  
  <pre><code>self.imageviewFondArticle.frame = CGRectMake((-((_imageviewFondArticle.frame.size.height*imageRatio)-320)/2),0, _imageviewFondArticle.frame.size.height*imageRatio, _imageviewFondArticle.frame.size.height);
  </code></pre>