How to call a delegate method from a class method in objective c?

Question

I want to call a delegate method from a class method.

My demo code

ClassA.h

@interface ClassA: NSObject<MyProtocol>

+ (void)demoMethod;
@property (nonatomic, weak) id<MyProtocol> delegate;

ClassA.m

+ (void)demoMethod {
    if ([self.delegate respondsToSelector:@selector(refreshViewController)]) {
                [self.delegate refreshViewController];
       }
  }

The error in above code is:

No member named 'delegate' in 'struct objc_class'
Member reference type 'struct objc_class *' is a pointer; did you mean to use '->'?

Please help me out to call a delegate method from a class method

Thanks!!!

Andreas Oetjen · Accepted Answer · 2020-07-17 05:40:29Z

1

You cannot access instance properties from a static (class) function.

In your case, in your demo method, self does not refer to an instance of ClassA, but to ClassA itself.

There is no general solution to this behaviour; they all are kind-of work-arounds, depending on your needs:

Keep a static reference to the instance (somehow a singleton approach)
Don't make demoMethod a static function
Keep the current / latest delegate in a static property and use this

answered Jul 17, 2020 at 5:40

Andreas Oetjen

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Comments

Cy-4AH · Accepted Answer · 2020-07-17 09:49:11Z

0

If you want access it from class then delegate should be class variable:

@interface ClassA: NSObject<MyProtocol>

+ (void)demoMethod;
@property (nonatomic, weak, class) id<MyProtocol> delegate;

answered Jul 17, 2020 at 9:49

Cy-4AH

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