label property is nil,container view - objective-c

Question

Situation:
3 view controllers, white is main, red and blue are embedded (container view controllers)
I select something in red,it switches to blue,I swipe the blue - it goes back and I want to change text in the label to some custom text
Sequence:
So I use delegation and it also works.But when I try to set label's text property(in the method that confirms my protocol) via self.thisLabel.text NSLog says this label is nil, although I have an outlet. If I use something like [self.view viewWithTag:tag] NSLog shows that label is there but I can't set the text, it stays the same.
code in white:
header
#interface ContactsViewController : UIViewController <BlueViewControllerDelegate>
implementation
- (void)adjustLabel:(NSString *)string{
NSLog(#"i am here baby %#",self.thisLabel);
[[self.view viewWithTag:57] setValue:string forKey:#"text"];
}
code in blue:
header:
#protocol BlueViewControllerDelegate <NSObject>
-(void)adjustLabel:(NSString*)string;
#end
and:
#property id<ViewControllerDelegate> delegate;
implementation
- (void)viewDidLoad{
[super viewDidLoad];
UIStoryboard *sB = [UIStoryboard storyboardWithName:#"Main" bundle:[NSBundle mainBundle]];
WhiteViewController *WhiteVc = [sB instantiateViewControllerWithIdentifier:#"whiteID"];
self.delegate = WhiteVc;
}
-(void)willMoveToParentViewController:(UIViewController *)parent{
[self.delegate adjustLabel:#"some custom text"];
}
-(IBAction)swipePerformed:(UISwipeGestureRecognizer*)sender{
[self willMoveToParentViewController:nil];
[self.view removeFromSuperview];
[self removeFromParentViewController];
}
Any thoughts?

Answer 1

If I understand your VC hierarchy correctly, the WhiteViewController is the parent of BlueViewController, so you shouldn't instantiate a new one from the storyboard in viewDidLoad but do instead:
WhiteViewController *whiteVc = (WhiteViewController*)self.parentViewController;
self.delegate = whiteVC;
Also, I don't find overriding willMoveToParentViewController particularly useful. You could put your delegate call to your swipe action.