CODEWITHSUNDEEP
iosobjective-cdelegates
Robert J. Clegg
Robert J. Clegg

Reputation: 7360

Delegate method not firing?

Just when I thought I had my head around how delegates work, it seems I am missing something.

I've setup a delegate like so:

ViewControllerA.h

@protocol LoginDelegate <NSObject>

-(void)userLoginSuccessful;

@end
@interface BBLoginViewController : BBBaseViewController
@property (weak, nonatomic) id <LoginDelegate> delegate; 

@end

ViewControllerA.m

-(void)someMethod 
{
    if ([self.delegate respondsToSelector:@selector(userLoginSuccessful)]){
                [self.delegate userLoginSuccessful];
            }
        [self dismissViewControllerAnimated:YES completion:nil];

}

ViewControllerB.m

    #import "ViewControllerA.h"

    @interface ViewControllerB () <UITableViewDataSource, UITableViewDelegate, LoginDelegate>


    -(void)viewWillAppear:(BOOL)animated
    {

        ViewControllerA *loginViewController = [[ViewControllerA alloc]init];
        loginViewController.delegate = self;

    }

#pragma mark - Login Delegate

-(void) userLoginSuccessful
{
  NSLog (@"Delegate fired!");
}

After all this my delegate method does not fire. What am I doing wrong? I looked at this SO answer and when checking the delegate is not nil - it is not. Its set to ViewControllerB.

Upvotes: 0

Views: 864

Answers (2)

Anil Varghese
Anil Varghese

Reputation: 42977

Set the delgate before presenting ViewControllerB. The below code is not required anymore 

-(void)viewWillAppear:(BOOL)animated
  {
     ViewControllerA *loginViewController = [[ViewControllerA alloc]init];
     loginViewController.delegate = self;

  }

Dont do like that. It will give you unexpected results. Remember always set the delegate before moving to the next view. If you are presenting modally just before presentViewController of if you are using segue in prepareForSegue

Upvotes: 2

trojanfoe
trojanfoe

Reputation: 122391

This code:

-(void)viewWillAppear:(BOOL)animated
{

    ViewControllerA *loginViewController = [[ViewControllerA alloc]init];
    loginViewController.delegate = self;

}

Will create a ViewControllerA object and then (almost) immediately destroy it and is not what you intended.

You probably want to be setting the delegate in the prepareForSegue: method anyway...

Upvotes: 3

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