title: Unrecognized selector error when implementing a valueChanged action from a UISlider
body: <p>I have a very simple subclass of <code>UIViewController</code>: </p>
  
  <pre><code>@interface RoastChickenViewController : UIViewController {
      IBOutlet UISlider *weightSlider;    
  }
  
  @property (nonatomic,retain) UILabel *cookingTimeLabel;
  - (void) weightValueHasChanged:(id)sender;
  @end
  </code></pre>
  
  <p>My xib file is set to have a <code>RoastChickenViewController</code> as it's File's owner type and the <code>weightSlider</code> is connected and the 'valueChanged' action is connected to <code>weightValuHasChanged:</code>. </p>
  
  <p>Trouble is as soon as I touch the slider (simulator or device) I get:</p>
  
  <pre><code>2010-08-21 20:26:07.688 CookIt1[26682:207] -[NSCFString weightValueHasChanged:]: unrecognized selector sent to instance 0x59215e0
  2010-08-21 20:26:07.690 CookIt1[26682:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFString weightValueHasChanged:]: unrecognized selector sent to instance 0x59215e0'
  *** Call stack at first throw:
  (
      0   CoreFoundation                      0x02395919 __exceptionPreprocess + 185
      1   libobjc.A.dylib                     0x024e35de objc_exception_throw + 47
      2   CoreFoundation                      0x0239742b -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
      3   CoreFoundation                      0x02307116 ___forwarding___ + 966
      4   CoreFoundation                      0x02306cd2 _CF_forwarding_prep_0 + 50
      5   UIKit                               0x002b9e14 -[UIApplication sendAction:to:from:forEvent:] + 119
      6   UIKit                               0x003436c8 -[UIControl sendAction:to:forEvent:] + 67
      7   UIKit                               0x00345b4a -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 527
      8   UIKit                               0x003c23ac -[UISlider beginTrackingWithTouch:withEvent:] + 731
  </code></pre>
  
  <p>A little bit of history, I actually had this working using having subclassed UIView directly. I have managed to break it on converting in from a UIView to a UIViewController, which I guess is the more natural way to implement simple behavior like this.</p>
  
  <p>Is there some sort of check list I can apply as there is obviously something I'm missing.</p>