为什么此代码会导致内存泄漏？

Question

I execute this code in my applicationDidBecomeActive callback.

- (void)applicationDidBecomeActive:(UIApplication *)application{
     [self showMainWindow];
}


- (void) showMainWindow{
      PushNotificationTabBarController *pushNotificationTabBarController = [[PushNotificationTabBarController alloc] initWithNibName:@"PushNotificationTabBarController" bundle:nil];
      self.viewDeckController.centerController = 
          pushNotificationTabBarController; // registered for Notification via addObserver...
}

The setter is defined like this:

@property (nonatomic, strong) IBOutlet UIViewController* centerController;

IIViewDeckController property in my AppDelegate :

@property (strong, nonatomic) IIViewDeckController *viewDeckController;

I found out that I have 2 PushNotificationTabBarController objects when I close and re-enter the app, with no reference to one of them, like a memory leak. However I dont understand why this code is causing it because to me it seems ok. I'm using ARC .

Answer 1

Before setting pushNotificationTabBarController check for self.viewDeckController.centerController object. If it exists, release and assigned to nil and assign new object of 'pushNotificationTabBarController'

 id controller = self.viewDeckController.centerController;
    if (controller) {
 [controller release];
  controller = nil;
}

  self.viewDeckController.centerController = pushNotificationTabBarController;