title: NSString stringwithFormat memory leak with ARC
body: <p>Hi I'm dealing with a memory leak but I cannot figure out what problem it is (I don't have either much experience with instruments so please excuse me if I'm asking something obvious).</p>
  
  <p>Basically I have two strings as properties in my class, the very first that will be shown to the user is retrieved in the main queue, and the one that is not required immediately is retrieved in a background queue: </p>
  
  <pre><code>@property (nonatomic, strong) NSString *stringDefaultLocationAddress;
  @property (nonatomic, strong) NSString *stringCurrentLocationAddress;
  
  -(void)viewDidLoad{
    ...
             dispatch_async(idQueue, ^(void) {
              [self recuperaDireccionActualEnBackground:currentUserLocation.coordinate];
           });
  
  }
  
  - (void)dealloc{
      [self removeObserver:self forKeyPath:@"playerProfileNeedsUpdate"];
      self.stringCurrentLocationAddress = nil;
      self.stringDefaultLocationAddress = nil;
  }
  </code></pre>
  
  <p>But I'm getting this leak in instruments:
  <a href="https://i.stack.imgur.com/Zyydk.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Zyydk.png" alt="code leak"></a>
  <a href="https://i.stack.imgur.com/7wCiC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7wCiC.png" alt="enter image description here"></a></p>
  
  <p>The problem has to do with the placeholders @" %@..." in stringWithFormat, because if I just put @"Test" at that  point the leak is gone, but I don't know why is leaking this and I would like to understand it.</p>
  
  <p>Thanks in advance.</p>