title: PerformSelector warning
body: <p>I'm receiving  a warning </p>
  
  <blockquote>
    <p>PerformSelector may cause a leak because its selector is unknown</p>
  </blockquote>
  
  <p><strong>In the code:</strong></p>
  
  <pre><code>- (void) callDelegate: (SEL) selector withArg: (id) arg error: (NSError*) err
  {
      assert([NSThread isMainThread]);
      if([delegate respondsToSelector: selector])
      {
          if(arg != NULL)
          {
              //this line the warning
              [delegate performSelector: selector 
                             withObject: arg 
                             withObject: err]; 
          }
          else
          {
              //this line the warning
              [delegate performSelector: selector 
                             withObject: err]; 
          }
      }
      else
      {
          NSLog(@"Missed Method");
      }
  }
  </code></pre>
  
  <p><strong>Header:</strong></p>
  
  <pre><code>@interface Topscore : UIViewController &lt;NSObject&gt; {
  
  //
  }
  </code></pre>