title: Cannot use respondsToSelector using ARC on Mac
body: <p>When I call <code>respondsToSelector</code> in an ARC environment, I get the following error message <code>Automatic Reference Counting Issue</code> <code>No known instance method for selector respondsToSelector:</code></p>
  
  <p>This is the header</p>
  
  <pre><code>#import &lt;AppKit/AppKit.h&gt;
  
  
  @class MTScrollView;
  
  @protocol MTScrollViewDelegate
  -(void)scrollViewDidScroll:(MTScrollView *)scrollView;
  @end
  
  
  @interface MTScrollView : NSScrollView 
  {
  
  }
  
  @property(nonatomic, weak) id&lt;MTScrollViewDelegate&gt;delegate;
  
  @end
  </code></pre>
  
  <p>This is the implementation file</p>
  
  <pre><code>#import "MTScrollView.h"
  
  @implementation MTScrollView
  
  @synthesize delegate;
  
  
  - (void)reflectScrolledClipView:(NSClipView *)aClipView
  {
      [super reflectScrolledClipView:aClipView];
  
      if([delegate respondsToSelector:@selector(scrollViewDidScroll:)])
      {
          [delegate scrollViewDidScroll:self];
      }
  }
  
  @end
  </code></pre>
  
  <p>Any suggestions on why I am getting this error?</p>