title: iOS App Exception - Terminating app due to uncaught exception 'NSInvalidArgumentException'
body: <p>I am getting the following exception, which is terminating the app.</p>
  
  <blockquote>
    <p>Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM objectForKey:]: unrecognized selector sent to instance 0x7abe4f90'</p>
  </blockquote>
  
  <p>Following is the code:</p>
  
  <pre><code>- (NSMutableData*)dataForConnection:(URLConnection*)connection {       
  NSMutableData *data = [receivedData objectForKey:connection.tagKey]; // Exception Here
  return data;
  }
  </code></pre>
  
  <p>Could anyone please suggest how to fix it? Thank you in advance!</p>