Extending a delegate from a base class

Question

I have an objc base class:

@protocol BaseClassDelegate;

@interface BaseClass : NSObject

@property (nonatomic, weak) id  delegate;         


        

Answer 1

I'd either create a wrapper delegate to make it the correct type in SubClass.

class SubClass: BaseClass {
    var myDelegate: SubClassDelegate? {
        get { return delegate as? SubClassDelegate }
        set { delegate = newValue }
    }
    @IBAction func onDoSomething(sender: AnyObject) {
        myDelegate?.additionalSubClassDelegateMethod();
    }
}

Or simply cast the delegate to the expected type:

(delegate as? SubClassDelegate)?.additionalSubClassDelegateMethod();

Answer 2

Here's a more comprehensive example of how to do this. Thanks to redent84 for pointing me in the right direction.

protocol SubclassDelegate: ClassDelegate {
    func subclassDelegateMethod()
}

class Subclass: Class {
    // here we assume that super.delegate property exists
    @IBAction func buttonPressedOrSomeOtherTrigger() {
        if let delegate: SubclassDelegate = self.delegate as? SubclassDelegate {
            delegate.subclassDelegateMethod()
        }
    }
}

And then in your implementation:

extension SomeOtherClass: SubclassDelegate {
    let someObject = Subclass()
    someObject.delegate = self

    func subclassDelegateMethod() {
        // yay! 
    }
}