title: performselector afterdelay not working
body: <p>i am using the following method in a uiview subclass:</p>
  
  <pre><code>[self performSelector:@selector(timeout) withObject:nil afterDelay:20];
  </code></pre>
  
  <p>The method is called after 20 seconds as expected.
  In another method i try to cancel the perform request using the following code:</p>
  
  <pre><code>[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(timeout) object:nil];
  </code></pre>
  
  <p>i've also tried </p>
  
  <pre><code>[NSRunLoop cancelPreviousPerformRequestsWithTarget:self selector:@selector(timeout) object:nil];
  </code></pre>
  
  <p>both messages don't bring the expected result an the timeout method is still called.
  can anybody explain me what i am doing wrong and how to do it the right way ?</p>
  
  <p>cheers from austria
  martin</p>