CODEWITHSUNDEEP
iosobjective-c
user788507
user788507

Reputation:

Trouble getting delegate working in ios

I'm just starting to learn Objective-C and I'm not 100% on all the syntax yet, and I think that might be where I'm having trouble, then again I'm not sure. I'm trying to get one view controller to send a message to its parent/callee view controller. I have it set up like this:

//ParentViewController.h

#import "SubViewController.h"

@interface ParentViewController : UIViewController <SubViewControllerDelegate>

- (void) sendMessageToParent:(NSInteger)num;

@end

This is the implementation:

//ParentViewController.m

@implementation ParentViewController

- (void) sendMessageToParent:(NSInteger)num
{
    NSLog(@"Message is %d", num);
}

- (void) buttonPushed
{
    [self performSegueWithIdentifier:@"SubView" sender:sender];
}

@end

Here's the other view controller setup:

//SubViewController.h

@protocol SubViewControllerDelegate <NSObject>

- (void) sendMessageToParent:(NSInteger)num;

@end

@interface SubViewController : UIViewController

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

@end

And implementation:

//SubViewController.m

@implementation SubViewController

@synthesize delegate;

- (void) something
{
    [self.delegate sendMessageToParent:4];
    [self.dismissViewControllerAnimated:YES completion:nil];
}

Appreciate any help, thanks.

Upvotes: 0

Views: 44

Answers (3)

Alfie Hanssen
Alfie Hanssen

Reputation: 17094

Looks like you're not setting SubViewController's delegate to SuperViewController. You'd do this typically when you instantiate SubViewController. e.g. subViewController.delegate = self

ParentViewController.h

@interface ParentViewController : UIViewController

@end

ParentViewController.m

@implementation ParentViewController <SubViewControllerDelegate> // Better to place this in .m than .h

#pragma mark - SubViewController Delegate

- (void)sendMessageToParent:(NSInteger)num
{
    NSLog(@"Message is %d", num);
}

- (void)buttonPushed
{
    [self performSegueWithIdentifier:@"SubView" sender:sender];
}

@end

SubViewController.h

@protocol SubViewControllerDelegate <NSObject>

- (void)sendMessageToParent:(NSInteger)num;

@end

@interface SubViewController : UIViewController

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

@end

SubViewController.m

@implementation SubViewController

// @synthesize delegate; // Not necessary, old fashioned

- (void)something
{
    // Set a breakpoint here and step through, you're not setting your delegate, so this conditional is not being hit
    if (self.delegate && [self.delegate respondsToSelector:@selector(sendMessageToParent:)])
    {
        [self.delegate sendMessageToParent:4];         
    }

    [self.dismissViewControllerAnimated:YES completion:nil];
}

Upvotes: 0

Jonathan Vukovich-Tribouharet
Jonathan Vukovich-Tribouharet

Reputation: 1988

You need to add to ParentViewController:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([[segue identifier] isEqualToString:@"SubView"])
    {
        SubViewController *vc = [segue destinationViewController];
        vc.delegate = self;
    }
}

Upvotes: 4

sha
sha

Reputation: 17850

You need to add handler for prepareForSegue and set .delegate properly there. I don't think your SubviewController has delegate set to the parent one.

Upvotes: 0

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