title: NSJSONSerialization bug?
body: <p>Been trying to debug a crash for the past 10 hours and finally, I simplified it to this code:</p>
  
  <pre><code>NSError *error = nil;
  NSData *data = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"payload" ofType:@"txt"]];
  id obj = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&amp;error];
  </code></pre>
  
  <p>With NSZombieEnabled, this crashes the app at the third line (where the parsing happens) and it logs:</p>
  
  <pre><code>*** -[CFString retain]: message sent to deallocated instance 0x758afa0
  </code></pre>
  
  <p>The contents of <code>payload.txt</code> are:</p>
  
  <pre><code>[
     {
        "created_at":"2013-02-15T23:46:02-05:00",
        "description":"Take out the Big Gun sounded simple enough, except the Strogg were waiting. You, and a few marines like you, are the lucky ones. You've made it down in one piece and are still able to contact the fleet. The Gravity Well, the Strogg's newest weapon in its arsenal against mankind, is operational. With the fleet around Stroggos, 5% of ground forces surviving, and that number dwindling by the second, your orders have changed: free your comrades. Destroy the Gravity Well.Minimum: A 100% Windows XP/Vista-compatible computer system",
        "developer":"id Software",
        "external_id":"2340",
        "id":745,
        "image":"http://cdn.steampowered.com/v/gfx/apps/2340/header_292x136.jpg",
        "is_subscribed":0,
        "link":"http://store.steampowered.com/app/2340/",
        "price":"4.99",
        "seller_id":2,
        "thumb":"http://media.steampowered.com/steamcommunity/public/images/apps/2340/5bd6e22ffdf72fdfb5ce2092fa50150de5fbb56f.jpg",
        "title":"Quake II: Ground Zero",
        "updated_at":"2013-02-15T23:46:02-05:00",
        "is_subscribed":0
     },
     {
        "created_at":"2013-02-15T23:45:59-05:00",
        "description":"Rage through 32 single player levels and 6 deathmatch levels of sheer terror and fully immersive sound and lighting. Arm yourself against the cannibalistic Ogre, fiendish Vore and indestructible Schambler using lethal nails, fierce Thunderbolts and abominable Rocket and Grenade Launchers.Minimum: A 100% Windows XP/Vista-compatible computer system",
        "developer":"id Software",
        "external_id":"2310",
        "id":742,
        "image":"http://cdn.steampowered.com/v/gfx/apps/2310/header_292x136.jpg",
        "is_subscribed":0,
        "link":"http://store.steampowered.com/app/2310/",
        "price":"9.99",
        "seller_id":2,
        "thumb":"http://media.steampowered.com/steamcommunity/public/images/apps/2310/e5bdf8dc7759c573fe525d45b69011f6a173a984.jpg",
        "title":"Quake",
        "updated_at":"2013-02-15T23:45:59-05:00",
        "is_subscribed":0
     }
  ]
  </code></pre>
  
  <p>It's just an array of 2 dictionaries. I am not sure what's causing this crash/what's wrong with this JSON. </p>
  
  <p><strong>UPDATE</strong> Removing <code>"is_subscribed":0</code> in the first object in the array gets rid of the crash.</p>