title: Weak Property Of ViewController is not set some time
body: <p>I'm using MMDrawerController And want passing data from one view controller to Another view controller as(HomeViewController to DetailViewController)</p>
  
  <p><em>HomeViewController view controller</em>  </p>
  
  <pre><code>Category *categoryItem = [category objectAtIndex:cellIndex];
           UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle: nil];
          DetailsViewController * centerVC=(DetailsViewController*)[storyboard instantiateViewControllerWithIdentifier:@"DetailsViewController"];
                      centerVC.catName= categoryItem.name ;
              centerVC.catUrl=categoryItem.url;
              UINavigationController * centerNav=[[UINavigationController alloc]initWithRootViewController:centerVC];
              AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
              appDelegate.drawerController.centerViewController=centerNav;
  </code></pre>
  
  <p>And In ViewDidLoad We Want access property as
  <em>DetailsViewController view controller</em>
  <strong>DetailsViewController.h</strong></p>
  
  <pre><code>@property (nonatomic,weak) NSString* catName;
  @property (nonatomic,weak) NSString* catUrl;
  
  - (void)viewDidLoad {
      [super viewDidLoad];
  
  self.navigationItem.title = [_catName uppercaseString];
  
  }
  </code></pre>
  
  <p>But some time _catName has value nil.</p>
  
  <p>Is there anything wrong ,If Then plz suggest.</p>
  
  <p>If problem with defining properties weak then what type property I choose for view controller property.</p>