title: NSMutableArray leaks warning addressed by the Instrument
body: <p>I am using Instrument leaks tools to check leaks in the code.</p>
  
  <pre><code>//MyClass.h
  @property (nonatomic, retain) NSMutableArray *marrProperty;
  
  //MyClass.m
  NSSortDescriptor *createdTime = [[NSSortDescriptor alloc] initWithKey:@"createdTime" ascending:NO selector:@selector(compare:)];             
  NSArray *sortedArray = [self.anManagedObj.aRelationships sortedArrayUsingDescriptors:[NSArray arrayWithObject:createdTime]];
  [createdTime release];
  NSMutableArray *marr = [[NSMutableArray alloc] initWithArray:sortedArray];
  self.marrProperty = marr;
  [marr release];
  </code></pre>
  
  <p>After checking with the leaks tool in Instrument, I was told the leaks happened in the following code:</p>
  
  <pre><code>NSMutableArray *marr = [[NSMutableArray alloc] initWithArray:sortedArray];
  self.marrProperty = marr;
  </code></pre>
  
  <p>I don't know why, because I just alloc and release well.</p>