title: Why does calling -allValues on an NSDictionary throw an exception?
body: <p>I try to get all values from nsdictionary, but it throw an exception at second line    </p>
  
  <pre><code>NSDictionary* thetimeLineDict = [NSJSONSerialization JSONObjectWithData:responseData options:0 error:&amp;jsonParsingError];
  NSArray* theallTweets = [thetimeLineDict allValues];
  </code></pre>
  
  <p>below is the exception from console</p>
  
  <pre><code>2011-11-27 14:56:38.156 SparkTweet[2066:1390b] -[__NSCFArray allValues]: unrecognized selector sent to instance 0x8128310
  2011-11-27 14:56:38.158 SparkTweet[2066:1390b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFArray allValues]: unrecognized selector sent to instance 0x8128310'
  *** First throw call stack:
  (0x14c0052 0x189cd0a 0x14c1ced 0x1426f00 0x1426ce2 0x2c48 0x33306 0x1b38445 0x1b39ecf 0x1b39d28 0x1b394af 0x9b632b24 0x9b6346fe)
  terminate called throwing an exception
  </code></pre>
  
  <p>Why might this be happening?</p>