Where is the error in this code?

Question

Please tell the where is the error in this code.I don't want to call the method myMethodToDoStuff. Is there any other way it will work ?

MyClass.h file should look like this (add delegate lines with comments!)

#import <BlaClass/BlaClass.h>

@class MyClass;             //define class, so protocol can see MyClass
@protocol MyClassDelegate <NSObject>   //define delegate protocol
    - (void) myClassDelegateMethod: (MyClass *) sender;  //define delegate method to be implemented within another class
@end //end protocol

@interface MyClass : NSObject {
}
@property (nonatomic, weak) id <MyClassDelegate> delegate; //define MyClassDelegate as delegate

@end

MyClass.m file should look like this

#import "MyClass.h"
@implementation MyClass 
@synthesize delegate; //synthesise  MyClassDelegate delegate

- (void) myMethodToDoStuff {
    [self.delegate myClassDelegateMethod:self]; //this will call the method implemented in your other class    
}

@end

To use your delegate in another class (UIViewController called MyVC in this case) MyVC.h:

#import "MyClass.h"
@interface MyVC:UIViewController <MyClassDelegate> { //make it a delegate for MyClassDelegate
}

MyVC.m:

myClass.delegate = self;          //set its delegate to self somewhere

Implement delegate method

- (void) myClassDelegateMethod: (MyClass *) sender {
    NSLog(@"Delegates are great!");
}

It's not really clear what the issue is that you're having. Where is the code failing? — Allan Poole, Mar 21 '17 at 05:45
I want to know that for everyone else the code is working but not for me. I have copied the code from here. http://stackoverflow.com/a/12660523/7743539 — Harjot Singh Panesar, Mar 21 '17 at 05:47
I think you're misunderstanding how delegates work. Something inside MyClass will need to call myMethodToDoStuff in order for myClassDelegateMethod to get called. What is it you're trying to do exactly? — Allan Poole, Mar 21 '17 at 05:48
I think your right here. So the guy posted the code has missed some lines in his code. I totally get it now. — Harjot Singh Panesar, Mar 21 '17 at 05:49
I've added an answer showing one way of getting your delegate method called via myMethodToDoStuff :) — Allan Poole, Mar 21 '17 at 06:01

Allan Poole · Accepted Answer · 2017-03-21T06:00:12.787

There doesn't appear to be any error - this is a correct implementation of a delegate. In order to get myClassDelegateMethod: called, something inside MyClass will need to call myMethodToDoStuff. You could, for example, create another method that is publicly accessible, which calls myMethodToDoStuff. Then this method can be called in MyVC.

@interface MyClass : NSObject {
}
@property (nonatomic, weak) id <MyClassDelegate> delegate; //define MyClassDelegate as delegate

- (void) someOtherMethod;

@end

And in MyClass.m

#import "MyClass.h"
@implementation MyClass 
@synthesize delegate; //synthesise  MyClassDelegate delegate

 - (void) myMethodToDoStuff {
    [self.delegate myClassDelegateMethod:self]; //this will call the method implemented in your other class    
}

 - (void) someOtherMethod {
     [self myMethodToDoStuff];
 }

@end

And finally in MyVC:

myClass.delegate = self;          //set its delegate to self somewhere
[myClass someOtherMethod];

Where is the error in this code?

1 Answers1