Why isn't my custom iPhone delegate working?

Question

Hi all,

I'm just trying to build a simple delegate, it compiles successfully but it doesn't seem to do anything right now. Please review my code below, both FirstViewContoller and SecondViewController have separate xib files, the SecondViewController has a button hooked up to the myMethod of course.

I've been learning my way around objective c and iPhone SDK for a couple of months, I've been using a book and lynda.com tutorial to aid, I actually copied most of the code using the xcode template for a utility app, and I believe I understand what is going on here, but is there something I've missed, as the button isn't responding.

If you need more info please ask.

Many thanks, Chris

SecondViewController.h

#import <UIKit/UIKit.h>

@protocol SecondViewControllerDelegate;


@interface SecondViewController : UIViewController {
    id <SecondViewControllerDelegate> delegate;
}

@property (nonatomic, assign) id <SecondViewControllerDelegate> delegate;


-(IBAction) myMethod;

@end

@protocol SecondViewControllerDelegate

-(void)viewControllerDidFinish:(SecondViewController *)controller;

@end

SecondViewController.m

@implementation SecondViewController

@synthesize delegate;

-(IBAction) myMethod
{
    [self.delegate viewControllerDidFinish:self];
}
//
@end

FirstViewController.h

@interface FirstViewController : UIViewController <SecondViewControllerDelegate>{
//
@end

FirstViewController.m

@implementation FirstViewController

-(void)viewControllerDidFinish:(SecondViewControllerDelegate *)controller
{
    NSLog(@"delegate is being used");
}
//
@end

Answer 1

Two things:

1. Your IBAction method myMethod, if it really is an IBAction, needs to take an argument: -(IBAction)myMethod:(id)sender Before you blame the delegate pattern, make sure that myMethod is being called (set a breakpoint and see).

2. Your delegate method seems to be declared to take a delegate type as a param, not a viewController which is what you seem to want to be passing there. That might all get obscured by the id types, but I think you probably want to rejigger the declarations.