Swift: Protocol method as Action in target-action

Question

I'd like to have a protocol:

protocol CameraButtonDelegate: class {
    func cameraButtonDidPress(_ sender: UIButton)
}

So, I could assign any client to a button, e.g.:

cameraButton.addTarget(delegate, action: #selector(cameraButtonDidPress), for: .touchUpInside)

However, it does not compile as I have to specify a particular function in action, e.g.:

cameraButton.addTarget(delegate, action: #selector(AAPLViewController.cameraButtonDidPress), for: .touchUpInside)

How to solve this issue, if I'd like to have multiple clients being targeted by a single button?

score 7 · Accepted Answer · answered Aug 14 '18 at 10:30

7

It should work if you make the protocol @objc

@objc protocol CameraButtonDelegate: class {
    func cameraButtonDidPress(_ sender: UIButton
}

and specify the selector as protocol method

cameraButtonDidPress.addTarget(delegate, action: #selector(CameraButtonDelegate.cameraButtonDidPress), for: .touchUpInside)

answered Aug 14 '18 at 10:30

vadian

if anyway the implementation will be written inside the class finally , then what is the need for the delegate here – Shehata Gamal Aug 14 '18 at 10:32
Works like a charm. – Richard Topchii Aug 14 '18 at 10:55

score 0 · Answer 2 · answered Aug 14 '18 at 10:24

0

You can try

cameraButton.addTarget(Service.shared, action: #selector(Service.shared.cameraButtonDidPress(_:)), for: .touchUpInside)

//

class Service {

   static let shared = Service()

    @objc func cameraButtonDidPress (_ sender:UIButton){


    }
}

answered Aug 14 '18 at 10:24

Shehata Gamal

Thank you, I'm looking for a more elegant solution, avoiding using the singleton. – Richard Topchii Aug 14 '18 at 10:27
Something, similar to this https://stackoverflow.com/questions/32760481/swift-protocol-as-type-as-target-of-button-action – Richard Topchii Aug 14 '18 at 10:27
if it's a duplicate and solved your problem then delete – Shehata Gamal Aug 14 '18 at 10:28
it's not since the Swift syntax has changed significantly and approach described in that answer doesn't work anymore. – Richard Topchii Aug 14 '18 at 10:44

2 Answers2