title: IPhone app terminating due to uncaught exception
body: <p>HI, 
  I am developing a iphone app by using cocos2d. Its shown this msg.</p>
  
  <pre><code>2009-01-26 16:17:40.603 Find The Nuts[449:20b] *** -[NSCFArray onTimer:]: unrecognized selector sent to instance 0x59be030
  2009-01-26 16:17:40.605 Find The Nuts[449:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSCFArray onTimer:]: unrecognized selector sent to instance 0x59be030'  
  </code></pre>
  
  <p>here onTimer is a count down timer method. what is the solution for it? </p>