title: Linking Label to IBOutlet gives NSUnknownKeyException
body: <p>I have created a TabBarView. On one of the tabs, I have a View with several <code>Labels</code> on it. It works fine.</p>
  
  <p>When I connect the Labels in Interface Builder to the File's Owner (the corresponding IBOutlets) then the App crashes with the following error when I open that tab:</p>
  
  <pre><code>2011-05-15 18:36:29.070 AeroNav[958:707] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[&lt;UIViewController 0x18afe0&gt; setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key speedLabel.'
  *** Call stack at first throw:
  (
  0   CoreFoundation                      0x312a664f __exceptionPreprocess + 114
  1   libobjc.A.dylib                     0x34a07c5d objc_exception_throw + 24
  2   CoreFoundation                      0x312a63cd -[NSException dealloc] + 0
  3   Foundation                          0x351c7edb -[NSObject(NSKeyValueCoding) setValue:forUndefinedKey:] + 182
  4   Foundation                          0x351809cb _NSSetUsingKeyValueSetter + 90
  5   Foundation                          0x35180217 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 194
  6   Foundation                          0x3516242f -[NSObject(NSKeyValueCoding) setValue:forKeyPath:] + 130
  7   UIKit                               0x369848df -[UIRuntimeOutletConnection connect] + 66
  8   CoreFoundation                      0x3123ed7b -[NSObject(NSObject) performSelector:] + 18
  9   CoreFoundation                      0x3123e99d -[NSArray makeObjectsPerformSelector:] + 388
  10  UIKit                               0x36983847 -[UINib instantiateWithOwner:options:] + 586
  11  UIKit                               0x36984e09 -[NSBundle(UINSBundleAdditions) loadNibNamed:owner:options:] + 92
  12  UIKit                               0x368fe5e9 -[UIViewController _loadViewFromNibNamed:bundle:] + 36
  13  UIKit                               0x368cbfa5 -[UIViewController loadView] + 80
  14  UIKit                               0x367b0ebf -[UIViewController view] + 30
  15  UIKit                               0x367ee1db -[UITabBarController transitionFromViewController:toViewController:transition:shouldSetSelected:] + 66
  16  UIKit                               0x367ee18d -[UITabBarController transitionFromViewController:toViewController:] + 32
  17  UIKit                               0x367eda33 -[UITabBarController _setSelectedViewController:] + 186
  18  UIKit                               0x36872ceb -[UITabBarController setSelectedViewController:] + 14
  19  UIKit                               0x36872be7 -[UITabBarController _tabBarItemClicked:] + 226
  20  CoreFoundation                      0x31216571 -[NSObject(NSObject) performSelector:withObject:withObject:] + 24
  21  UIKit                               0x36796ec9 -[UIApplication sendAction:to:from:forEvent:] + 84
  22  UIKit                               0x36796e69 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 32
  23  UIKit                               0x36872a8b -[UITabBar _sendAction:withEvent:] + 270
  24  CoreFoundation                      0x31216571 -[NSObject(NSObject) performSelector:withObject:withObject:] + 24
  25  UIKit                               0x36796ec9 -[UIApplication sendAction:to:from:forEvent:] + 84
  26  UIKit                               0x36796e69 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 32
  27  UIKit                               0x36796e3b -[UIControl sendAction:to:forEvent:] + 38
  28  UIKit                               0x36796b8d -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 356
  29  UIKit                               0x367d0bd9 -[UIControl sendActionsForControlEvents:] + 16
  30  UIKit                               0x36872815 -[UITabBar(Static) _buttonUp:] + 80
  31  CoreFoundation                      0x31216571 -[NSObject(NSObject) performSelector:withObject:withObject:] + 24
  32  UIKit                               0x36796ec9 -[UIApplication sendAction:to:from:forEvent:] + 84
  33  UIKit                               0x36796e69 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 32
  34  UIKit                               0x36796e3b -[UIControl sendAction:to:forEvent:] + 38
  35  UIKit                               0x36796b8d -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 356
  36  UIKit                               0x36797423 -[UIControl touchesEnded:withEvent:] + 342
  37  UIKit                               0x36795bf5 -[UIWindow _sendTouchesForEvent:] + 368
  38  UIKit                               0x3679556f -[UIWindow sendEvent:] + 262
  39  UIKit                               0x3677e313 -[UIApplication sendEvent:] + 298
  40  UIKit                               0x3677dc53 _UIApplicationHandleEvent + 5090
  41  GraphicsServices                    0x36452e77 PurpleEventCallback + 666
  42  CoreFoundation                      0x3127da97 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 26
  43  CoreFoundation                      0x3127f83f __CFRunLoopDoSource1 + 166
  44  CoreFoundation                      0x3128060d __CFRunLoopRun + 520
  45  CoreFoundation                      0x31210ec3 CFRunLoopRunSpecific + 230
  46  CoreFoundation                      0x31210dcb CFRunLoopRunInMode + 58
  47  GraphicsServices                    0x3645241f GSEventRunModal + 114
  48  GraphicsServices                    0x364524cb GSEventRun + 62
  49  UIKit                               0x367a8d69 -[UIApplication _run] + 404
  50  UIKit                               0x367a6807 UIApplicationMain + 670
  51  AeroNav                             0x00002423 main + 70
  52  AeroNav                             0x000023d8 start + 40
  )
  terminate called after throwing an instance of 'NSException'
  </code></pre>
  
  <p>I have read that it can be related to the xib not matching (correctly connected) to its view controller. I have no idea how to check or fix that?</p>
  
  <p>This is how my header file looks:</p>
  
  <pre><code>//Stats.h
  #import &lt;UIKit/UIKit.h&gt;
  @interface Stats : UIViewController
  {
      IBOutlet UILabel *speedLabel;
      IBOutlet UILabel *headingLabel;
  }
  @end
  </code></pre>
  
  <p>If anybody has any tips or links to other similar posts, I would appreciate it!</p>
  
  <p>Thank you in advance!</p>