Swift delegate for a generic class

Question

I have a class that needs to call out to a delegate when one of its properties changes. Here are the simplified class and protocol for the delegate:

protocol MyC         


        

Answer 1

You can use templates methods with type erasure...

protocol HeavyDelegate : class {
  func heavy(heavy: Heavy, shouldReturn: P) -> R
}  

class Heavy {
    typealias Param = P
    typealias Return = R
    weak var delegate : HeavyDelegate?  
    func inject(p : P) -> R? {  
        if delegate != nil {
            return delegate?.heavy(self, shouldReturn: p)
        }  
        return nil  
    }
    func callMe(r : Return) {
    }
}
class Delegate : HeavyDelegate {
    typealias H = Heavy<(Int, String), String>

    func heavy(heavy: Heavy, shouldReturn: P) -> R {
        let h = heavy as! H // Compile gives warning but still works!
        h.callMe("Hello")
        print("Invoked")
        return "Hello" as! R
    }  
}

let heavy = Heavy<(Int, String), String>()
let delegate = Delegate()
heavy.delegate = delegate
heavy.inject((5, "alive"))