title: resetting contents of NSMutableDictionary iVar
body: <p>I have an ivar I'll call dictionaryIvar, which is a mutable dictionary. Occasionally, its contents must be erased and reset with new contents. The contents are added over several iterations of indefinite quantity, hence why it is mutable.</p>
  
  <p>Is it enough to "reset" or release the dictionary with:</p>
  
  <pre><code> self.dictionaryIvar=nil;
  </code></pre>
  
  <p>And then in a different method, where needed, recreate the dictionary with:</p>
  
  <pre><code> if(!self.dictionaryIvar){
   self.dictionaryIvar = [NSMutableDictionary dictionary];
   }
  </code></pre>
  
  <p>Would this be acceptable, or would this leak the object?</p>