title: App crashes with error unrecognized selector sent to instance
body: <p>I am having an unrecognized selector sent to instance issue. I know which line I am having problem with, but I don't understand why it doesn't recognize it. (I tested this code in when I was creating my container views and it works just fine. But for some reason when I merge it to my main project I am getting this error.)</p>
  
  <p>This is my console output:</p>
  
  <pre><code>2013-12-20 16:47:59.633[8545:70b] -[UIViewController decideViewController:]: unrecognized selector sent to instance 0x8b5c250
  2013-12-20 16:47:59.659[8545:70b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIViewController decideViewController:]: unrecognized selector sent to instance 0x8b5c250'
  *** First throw call stack:
  (
      0   CoreFoundation                      0x01c075e4 __exceptionPreprocess + 180
      1   libobjc.A.dylib                     0x0198a8b6 objc_exception_throw + 44
      2   CoreFoundation                      0x01ca4903 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
      3   CoreFoundation                      0x01bf790b ___forwarding___ + 1019
      4   CoreFoundation                      0x01bf74ee _CF_forwarding_prep_0 + 14
      5   TProduct                          0x0000566f -[GameViewController changeViews:] + 143
      6   TProduct                          0x00005404 -[GameViewController timerTick:] + 532
      7   Foundation                          0x015c1927 __NSFireTimer + 97
      8   CoreFoundation                      0x01bc5bd6 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 22
      9   CoreFoundation                      0x01bc55bd __CFRunLoopDoTimer + 1181
      10  CoreFoundation                      0x01bad628 __CFRunLoopRun + 1816
      11  CoreFoundation                      0x01bacac3 CFRunLoopRunSpecific + 467
      12  CoreFoundation                      0x01bac8db CFRunLoopRunInMode + 123
      13  GraphicsServices                    0x0387b9e2 GSEventRunModal + 192
      14  GraphicsServices                    0x0387b809 GSEventRun + 104
      15  UIKit                               0x006f8d3b UIApplicationMain + 1225
      16  TProduct                          0x000070fd main + 141
      17  libdyld.dylib                       0x0224570d start + 1
  )
  libc++abi.dylib: terminating with uncaught exception of type NSException
  </code></pre>
  
  <p>and this is the part that it doesn't recognize
  GameViewController.m</p>
  
  <pre><code>-(void)changeViews:(NSString *)gameStateSegueIdentifier
  {
      NSLog(@"show view gameStateSegueIdentifier :%@",gameStateSegueIdentifier);
      [self.containerController decideViewController:gameStateSegueIdentifier];
  }
  </code></pre>
  
  <p>and this is the method I am calling 
  ContainerViewController.m</p>
  
  <pre><code>-(void)decideViewController:(NSString *)gameStateSegueIdentifier
  {
      if (gameStateSegueIdentifier == _currentSegueIdentifier) {
          return;
      }
  
      while (gameStateSegueIdentifier != _currentSegueIdentifier) {
          NSLog(@"this is the gameStateSegueIdentifier %@",gameStateSegueIdentifier);
          NSLog(@"this is the currentSegueIdentifier %@",_currentSegueIdentifier);
  
          [self changeViewControllers];
      }
  }
  </code></pre>
  
  <p>I understand that there are lots of "unrecognized selector sent to instance" questions already. But so far, I wasn't able to find an answer for my case. I appreciate the help.</p>