title: ContinueTrackingWithTouch doesn't get called continuously
body: <p>I am creating a subclass of <code>UIControl</code> and adding to my view controller's view </p>
  
  <pre><code>- (BOOL) beginTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event;
  - (BOOL) continueTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event;
  - (void) endTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event;
  </code></pre>
  
  <p>when I touch and track inside of view the <code>continueTrackingWithTouch</code>get called continuously but some point it doesn't get called even If I am tracking...</p>
  
  <p>Thanks in advance...</p>