title: UIButton touch down action not called when touch down but called when touch moved
body: <p>Hi need to perform an action when user touched DOWN the UIButton</p>
  
  <pre><code>[button addTarget:self action:@selector(touchDown:event:) forControlEvents:UIControlEventTouchDown];
  [button addTarget:self action:@selector(drag:event:) forControlEvents:UIControlEventTouchDragInside];
  [button addTarget:self action:@selector(drag:event:) forControlEvents:UIControlEventTouchDragOutside];
  [button addTarget:self action:@selector(touchUp:event:) forControlEvents:UIControlEventTouchUpInside];
  [button addTarget:self action:@selector(touchUp:event:) forControlEvents:UIControlEventTouchUpOutside];
  
  - (void)touchDown:(UIButton *)sender event:(UIEvent *)event {
      //begin only called when I move my finger 
  }
  
  
  - (void)drag:(UIButton *)sender event:(UIEvent *)event {
      //called when I move my finger, after touchDown was called
  }
  - (void)touchUp:(UIButton *)sender event:(UIEvent *)event {
  
  }
  </code></pre>
  
  <p>The root view controller of my app is tabbarviewcontroller, and each tab is a navigation view controller. in the viewWillAppear method of the chatting scene I hide the tab bar.   </p>
  
  <p>the result is, on device, when i touch down, it's not called, and when I move my finger a bit, it is called. </p>
  
  <p>Note: </p>
  
  <ol>
  <li><p>using Long Press gesture recognizer does not work either. </p></li>
  <li><p>If I put the button away from tab bar area, it works on device. </p></li>
  <li><p>on simulator, everything is fine. </p></li>
  </ol>
  
  <p>I created a sample project: 
  <a href="https://drive.google.com/folderview?id=0B_9_90avvmZtRmRDeHFkbFJLaFk&amp;usp=sharing" rel="noreferrer">https://drive.google.com/folderview?id=0B_9_90avvmZtRmRDeHFkbFJLaFk&amp;usp=sharing</a></p>