title: Crash on NSMutableDictionary's setObject function
body: <p>Here is my code:</p>
  
  <pre><code>NSLog(@"dictionaryPlayers=%@,%d",[dictionaryPlayers description],dictionaryPlayers.count);
  [dictionaryPlayers setObject:@"test" forKey:@"test2"];
  </code></pre>
  
  <p>dictionaryPlayers is inited in this class's init function:</p>
  
  <pre><code>-(id)init{
    ...
    dictionaryPlayers = [[NSMutableDictionary dictionaryWithCapacity:10]retain];
    ...
  }
  </code></pre>
  
  <p>The program crashed:</p>
  
  <pre><code>Thread 1:Program received signal: "SIGABRT".
  </code></pre>
  
  <p>And in console:</p>
  
  <pre><code>2011-12-27 17:01:21.744 [25454:207] dictionaryPlayers={
  },0
  2011-12-27 17:01:21.745 [25454:207] -[__NSCFConstantString tick]: unrecognized selector sent to instance 0x199bcc
  </code></pre>
  
  <p>With the NSLog outputs, i think dictionaryPlayers is well inited. So I don't know why crashed...</p>