title: iOS app crashing in release mode, works in debug mode
body: <p>Recently my app started breaking if I create the .ipa file for AppStore release. It works fine if I run the same code in emulator or if I run it on my iPhone from xcode, but once I create the release package it crashes while opening a particular view controller. </p>
  
  <p>I went through few of the posts on Stackoverflow where people had similar problems and tried following things:  </p>
  
  <ul>
  <li>Setting <code>SWIFT_OPTIMIZATION_LEVEL = "-Onone";</code> for release mode</li>
  <li>Setting <code>GCC_OPTIMIZATION_LEVEL = 0;</code> for release mode</li>
  <li>Commenting out some of the UI components which were added recently</li>
  </ul>
  
  <p>Following is the log I got from the device:  </p>
  
  <pre><code>Incident Identifier: 4F30BFF1-71DC-4542-A330-F3786B3302A8
  CrashReporter Key:   f6fcec71c8263640bd75a0d18937c323d8a95b43
  Hardware Model:      iPhone8,1
  Process:             Dummy [633]
  Path:                /private/var/containers/Bundle/Application/370692A3-C880-4008-8C70-641801FB894A/Dummy.app/Dummy
  Identifier:          com.example.Dummy
  Version:             1.0.71 (1.0.71)
  Code Type:           ARM-64 (Native)
  Role:                Foreground
  Parent Process:      launchd [1]
  Coalition:           com.example.Dummy [741]
  
  
  Date/Time:           2017-10-09 18:08:28.2604 -0700
  Launch Time:         2017-10-09 18:07:45.3034 -0700
  OS Version:          iPhone OS 10.3.2 (14F89)
  Report Version:      104
  
  Exception Type:  EXC_BREAKPOINT (SIGTRAP)
  Exception Codes: 0x0000000000000001, 0x0000000100518448
  Termination Signal: Trace/BPT trap: 5
  Termination Reason: Namespace SIGNAL, Code 0x5
  Terminating Process: exc handler [0]
  Triggered by Thread:  0
  
  Filtered syslog:
  None found
  
  Thread 0 name:  Dispatch queue: com.apple.main-thread
  Thread 0 Crashed:
  0   libswiftCore.dylib              0x0000000100518448 0x1003c0000 + 1410120
  1   libswiftCore.dylib              0x0000000100518448 0x1003c0000 + 1410120
  2   Dummy                           0x00000001000e2e14 0x10003c000 + 683540
  3   Dummy                           0x00000001000e351c 0x10003c000 + 685340
  4   UIKit                           0x000000018b5d3ec0 -[UIViewController loadViewIfRequired] + 1036
  5   UIKit                           0x000000018b68bff0 -[UINavigationController _layoutViewController:] + 72
  6   UIKit                           0x000000018b68bec8 -[UINavigationController _updateScrollViewFromViewController:toViewController:] + 416
  7   UIKit                           0x000000018b68b1f8 -[UINavigationController _startTransition:fromViewController:toViewController:] + 144
  8   UIKit                           0x000000018b68ac2c -[UINavigationController _startDeferredTransitionIfNeeded:] + 856
  9   UIKit                           0x000000018b68a7e0 -[UINavigationController __viewWillLayoutSubviews] + 64
  10  UIKit                           0x000000018b68a744 -[UILayoutContainerView layoutSubviews] + 188
  11  UIKit                           0x000000018b5d107c -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1200
  12  QuartzCore                      0x00000001887c1274 -[CALayer layoutSublayers] + 148
  13  QuartzCore                      0x00000001887b5de8 CA::Layer::layout_if_needed(CA::Transaction*) + 292
  14  QuartzCore                      0x00000001887b5ca8 CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 32
  15  QuartzCore                      0x000000018873134c CA::Context::commit_transaction(CA::Transaction*) + 252
  16  QuartzCore                      0x00000001887583ac CA::Transaction::commit() + 504
  17  QuartzCore                      0x0000000188758e78 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 120
  18  CoreFoundation                  0x00000001854509a8 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32
  19  CoreFoundation                  0x000000018544e630 __CFRunLoopDoObservers + 372
  20  CoreFoundation                  0x000000018544ea7c __CFRunLoopRun + 956
  21  CoreFoundation                  0x000000018537eda4 CFRunLoopRunSpecific + 424
  22  GraphicsServices                0x0000000186de8074 GSEventRunModal + 100
  23  UIKit                           0x000000018b639058 UIApplicationMain + 208
  24  Dummy                           0x0000000100105f34 0x10003c000 + 827188
  25  libdyld.dylib                   0x000000018438d59c start + 4
  
  Thread 1:
  0   libsystem_pthread.dylib         0x0000000184562ca8 start_wqthread + 0
  
  Thread 2 name:  com.apple.uikit.eventfetch-thread
  Thread 2:
  0   libsystem_kernel.dylib          0x000000018447f224 mach_msg_trap + 8
  1   libsystem_kernel.dylib          0x000000018447f09c mach_msg + 72
  2   CoreFoundation                  0x0000000185450e90 __CFRunLoopServiceMachPort + 192
  3   CoreFoundation                  0x000000018544eae4 __CFRunLoopRun + 1060
  4   CoreFoundation                  0x000000018537eda4 CFRunLoopRunSpecific + 424
  5   Foundation                      0x0000000185e98d74 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 304
  6   Foundation                      0x0000000185eb9b44 -[NSRunLoop(NSRunLoop) runUntilDate:] + 96
  7   UIKit                           0x000000018bfc36a8 -[UIEventFetcher threadMain] + 136
  8   Foundation                      0x0000000185f962d8 __NSThread__start__ + 996
  9   libsystem_pthread.dylib         0x000000018456568c _pthread_body + 240
  10  libsystem_pthread.dylib         0x000000018456559c _pthread_body + 0
  11  libsystem_pthread.dylib         0x0000000184562cb4 thread_start + 4
  
  Thread 3:
  0   libsystem_kernel.dylib          0x000000018447f224 mach_msg_trap + 8
  1   libsystem_kernel.dylib          0x000000018447f09c mach_msg + 72
  2   Dummy                           0x000000010012fcf4 0x10003c000 + 998644
  3   libsystem_pthread.dylib         0x000000018456568c _pthread_body + 240
  4   libsystem_pthread.dylib         0x000000018456559c _pthread_body + 0
  5   libsystem_pthread.dylib         0x0000000184562cb4 thread_start + 4
  
  Thread 4 name:  com.apple.NSURLConnectionLoader
  Thread 4:
  0   libsystem_kernel.dylib          0x000000018447f224 mach_msg_trap + 8
  1   libsystem_kernel.dylib          0x000000018447f09c mach_msg + 72
  2   CoreFoundation                  0x0000000185450e90 __CFRunLoopServiceMachPort + 192
  3   CoreFoundation                  0x000000018544eae4 __CFRunLoopRun + 1060
  4   CoreFoundation                  0x000000018537eda4 CFRunLoopRunSpecific + 424
  5   CFNetwork                       0x0000000185b8adf4 +[NSURLConnection(Loader) _resourceLoadLoop:] + 404
  6   Foundation                      0x0000000185f962d8 __NSThread__start__ + 996
  7   libsystem_pthread.dylib         0x000000018456568c _pthread_body + 240
  8   libsystem_pthread.dylib         0x000000018456559c _pthread_body + 0
  9   libsystem_pthread.dylib         0x0000000184562cb4 thread_start + 4
  
  Thread 5 name:  AVAudioSession Notify Thread
  Thread 5:
  0   libsystem_kernel.dylib          0x000000018447f224 mach_msg_trap + 8
  1   libsystem_kernel.dylib          0x000000018447f09c mach_msg + 72
  2   CoreFoundation                  0x0000000185450e90 __CFRunLoopServiceMachPort + 192
  3   CoreFoundation                  0x000000018544eae4 __CFRunLoopRun + 1060
  4   CoreFoundation                  0x000000018537eda4 CFRunLoopRunSpecific + 424
  5   AVFAudio                        0x000000019f6c2540 GenericRunLoopThread::Entry(void*) + 164
  6   AVFAudio                        0x000000019f6e8814 CAPThread::Entry(CAPThread*) + 84
  7   libsystem_pthread.dylib         0x000000018456568c _pthread_body + 240
  8   libsystem_pthread.dylib         0x000000018456559c _pthread_body + 0
  9   libsystem_pthread.dylib         0x0000000184562cb4 thread_start + 4
  
  Thread 6:
  0   libsystem_kernel.dylib          0x000000018449da88 __workq_kernreturn + 8
  1   libsystem_pthread.dylib         0x00000001845631a4 _pthread_wqthread + 1260
  2   libsystem_pthread.dylib         0x0000000184562cac start_wqthread + 4
  
  Thread 7:
  0   libsystem_pthread.dylib         0x0000000184562ca8 start_wqthread + 0
  
  Thread 8:
  0   libsystem_kernel.dylib          0x000000018449da88 __workq_kernreturn + 8
  1   libsystem_pthread.dylib         0x00000001845631a4 _pthread_wqthread + 1260
  2   libsystem_pthread.dylib         0x0000000184562cac start_wqthread + 4
  
  Thread 9:
  0   libsystem_pthread.dylib         0x0000000184562ca8 start_wqthread + 0
  
  Thread 0 crashed with ARM Thread State (64-bit):
      x0: 0x0000000100d20b80   x1: 0x00000001742ea580   x2: 0x0000000000000008   x3: 0x00000001844e32c0
      x4: 0x00000000ffb80038   x5: 0x0000000000000010   x6: 0x0048000004210103   x7: 0x0000000000000000
      x8: 0x00000001742e9980   x9: 0x00000001742e9980  x10: 0x0000000000000001  x11: 0xbaddc0dedeadbead
     x12: 0x0000010000000100  x13: 0x206e6120676e6970  x14: 0x6c616e6f6974704f  x15: 0x000a65756c617620
     x16: 0x00000001844d3a1c  x17: 0x0000000000000000  x18: 0x0000000000000000  x19: 0x0000000000000000
     x20: 0x0000000000000002  x21: 0x0000000000000039  x22: 0x000000010022ac40  x23: 0x0000000000000002
     x24: 0x000000000000000b  x25: 0x0000000100231dc8  x26: 0x0000000171a68480  x27: 0x00000001aa543000
     x28: 0x0000000000000001   fp: 0x000000016fdc0ee0   lr: 0x0000000100518448
      sp: 0x000000016fdc0ea0   pc: 0x0000000100518448 cpsr: 0x20000000
  </code></pre>
  
  <p>I am using Xcode Version 8.3.3 (8E3004b), Swift3. Please let me know if someone had similar issue before, or any guesses to fix this problem!</p>
  
  <p>Thanks!</p>