Question

I am trying to make a custom protocol that i hope somebody might help with.

I have a mainViewController (mainVC) that has a label. That label needs to be updated with a string when i press a button in edwwVC.

I am using ARC and storyboard.

The problem is when i press the Done Button on the edwwVC, the “done” method is called BUT the delegate method is not called in mainVC.
Whereas, if i call the done method VIA the mainVC, then the done method is called AND the delegate method. So I can see the connection is there, I just do not understand why the delegate method is not called when i press the done button in the edwwVC.

I imagine it has something to do with the init of the edwwVC. Because it is already initiated by storyboard, so it looks to me as if I am initializing it again the in the viewDidLoad method of the mainVC. But that is how far i got 🙂

Thanks in advance!

edwwVC.h

#import <UIKit/UIKit.h>
#import "IIViewDeckController.h"

@class EDWWViewController;

@protocol EDWWViewControllerDelegate <NSObject>;
@optional
- (void)edwwVCDidFinish:(EDWWViewController *)edwwVC;
@end

@interface EDWWViewController : UIViewController <IIViewDeckControllerDelegate> {
__weak  id<EDWWViewControllerDelegate> delegate;
NSMutableArray *edwwPoints;
}

@property (weak) id<EDWWViewControllerDelegate> delegate;
@property (weak, nonatomic) IBOutlet UITableView *theTableView;
@property (strong, nonatomic)     NSString *testString;
- (IBAction)done:(id)sender;
- (IBAction)add:(id)sender;
@end

edwwVC.m:

#pragma mark - delegate method
- (IBAction)done:(id)sender {
testString = @"This is the test string!";
[delegate edwwVCDidFinish:self];
[self.viewDeckController closeRightViewAnimated:YES];
NSLog(@"Done pressed");
}

MainVC.m:

- (void)viewDidLoad
{
[super viewDidLoad];
edwwViewController = [[EDWWViewController alloc] init];
edwwViewController.delegate = self;
}  

- (void)edwwVCDidFinish:(EDWWViewController *)edwwVC {    
edwwLabel.text= edwwVC.testString;    
NSLog(@"delegate method called");
}

Answer 1

Remove the line …

__weak  id<EDWWViewControllerDelegate> delegate;

From the .h and change the line…

[delegate edwwVCDidFinish:self];

to…

[self.delegate edwwVCDidFinish:self];

In the .m.

That should sort it.

The way you have it set up the ivar delegate is not the same as the property delegate (which is actually an ivar called _delegate) (thanks @Joris Kluivers, just adding for clarity). They are pointing to different things.

If you add a breakpoint where you are calling the delegate method I think you’ll find that delegate is nil. Whereas _delegate (or self.delegate) is not nil.

::EDIT::

Ahh… just spotted the second bit too.

If you are setting up the edwwvc in storyboard then you should be alloc initing it too.

If you are segue-ing to the edwwvc then you should intercept the segue in mainVC.m like this…

- (void)prepareForSegue: //blah the rest of the name...
{
    if ([segue.identifier isEqualToString:@"the name of your segue"])
    {
        EDWWViewController *controller = segue.destinationViewController;

        controller.delegate = self;
    }
}

This will take the controller that you are pushing to from the storyboard and set the delegate to it.

:: ANOTHER EDIT ::

If EDWWVC is inside a containerViewController then you can do this inside viewDidLoad in MainVC.m…

- (void)viewDidLoad
{
    // other stuff...

    for (UIViewController *controller in self.childViewControllers) {
        if ([controller isKindOfClass:[EDWWViewController class]]) {
            EDWWViewController *edwwvc = (EDWWViewController*)controller;

            eddwvc.delegate = self;
        }
    }
}

You may find this code has to go in viewDidAppear or something but I think viewDidLoad shouldd work just fine.

You may actually be able to set the delegate property directly by using the storyboard to (but I’m not 100% certain on this).