Link parent uiviewcontroller as delegate to uivewcontroller added by addChildViewController

Question

I'mm successfully embedding and swopping uiviewcontrollers within a container view. Now I want to send a message from the child uiviewcontrollers up to the parent uivewcontroller. I'm wiring them up as delegates but can't figure out how the assign it as a delegate in the parent view

parent.h -load delegate

// Import child delegates
#import "GenWarnDangerVC.h"

@interface Appliance_IPVC : UIViewController <ChildViewControllerDelegate>
{
}

parent.m -load child view

- (void)viewDidLoad
{
    [super viewDidLoad];

    // * Add child views

    [self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildFour"]];
    [self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildOne"]]; // <-- this is the delegate
    [self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildTwo"]];
    [self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildThree"]];

    self.currentChildController = self.childViewControllers[0];


    self.currentChildController.view.frame = self.containerView.bounds;
    [self.containerView addSubview:self.currentChildController.view];

    for (UIViewController *controller in self.childViewControllers)
        [controller didMoveToParentViewController:self];

    // Tried making it delegate here, complies but zilch happens
    UIStoryboard *storyboard = self.storyboard;
    GenWarnDangerVC *_GenWarnDangerVC  = [storyboard instantiateViewControllerWithIdentifier:@"ChildOne"];
    _GenWarnDangerVC.delegate=self;

}

We swop in later during runtime with

[self transitionFromViewController:oldController toViewController:newController duration:0.33 options:options animations:^{} completion:nil];

childview.h - do delegate setting up stuff

#import <UIKit/UIKit.h>

@protocol ChildViewControllerDelegate;

@interface GenWarnDangerVC : UIViewController <UITextViewDelegate>

@property (nonatomic, weak) id<ChildViewControllerDelegate> delegate;

@end


@protocol ChildViewControllerDelegate <NSObject>
- (void)animateTextField:(BOOL)up;
@end

childview.m - send message to parent

- (BOOL)textViewShouldBeginEditing:(UITextView *)textView;
{
    //if ([self.delegate respondsToSelector:@selector(animateTextField:)])
    //{
        // Sending delegate message
        NSLog(@"Sending delegate message");
        [self.delegate animateTextField:YES];
    //}

    return YES;
}

The parent view never responds, it handles [self animateTextField:YES] when called within the parent view (itself) but never 'hears' from the child.

I'm guessing because we need to tell the child view who it's a delegate for, in the parent view, with something like

UIStoryboard *storyboard = self.storyboard;
    GenWarnDangerVC *_GenWarnDangerVC  = [storyboard instantiateViewControllerWithIdentifier:@"ChildOne"];
    _GenWarnDangerVC.delegate=se

lf;

But (a) what exactly? And (b) is it done when the cild views are loaded? or when they are swapped in?

score 0 · Answer 1 · answered Apr 10 '13 at 19:47

The problem lay in how I was initialising the child controllers

[self addChildViewController:[self.storyboard instantiateViewControllerWithIdentifier:@"ChildOne"]];

This loaded the controller in but didn't leave a reference to itself so it could be assigned a delegate.

This however does. Yay.

GenWarnDangerVC * GenWarnDanger_vc = [self.storyboard instantiateViewControllerWithIdentifier:@"ChildOne"];
[self addChildViewController:GenWarnDanger_vc];
GenWarnDanger_vc.delegate = self;

Link parent uiviewcontroller as delegate to uivewcontroller added by addChildViewController

1 Answers1