Swift 2.2 #selector in protocol extension compiler error

Question

I've got a protocol extension it used to work perfectly before swift 2.2.

Now I have a warning that tells me to use the new #selector, but if I add it

no method declared with Objective-C Selector.

I tried to reproduce the issue in this few lines of code, that can be easily copy and paste also into playground

  protocol Tappable {     func addTapGestureRecognizer()     func tapGestureDetected(gesture:UITapGestureRecognizer) }  extension Tappable where Self: UIView {     func addTapGestureRecognizer() {         let gesture = UITapGestureRecognizer(target: self, action:#selector(Tappable.tapGestureDetected(_:)))         addGestureRecognizer(gesture)     } }  class TapView: UIView, Tappable {     func tapGestureDetected(gesture:UITapGestureRecognizer) {         print("Tapped")     } } 

There is also a suggestion to append to that method in the protocol @objc, but if I do it asks me also to add it to the class that implements it, but once I add the class doesn't conform to the protocol anymore, because it doesn't seems to see the implementation in the protocol extension.
How can I implement this correctly?

Answer 1

I had a similar problem. here is what I did.

1. Marked the protocol as @objc.
2. Marked any methods I extended with a default behavior as optional.

3. Then used Self. in the #selector.

   @objc public protocol UpdatableUserInterfaceType {   optional func startUpdateUITimer()   optional var updateInterval: NSTimeInterval { get }   func updateUI(notif: NSTimer) }  public extension UpdatableUserInterfaceType where Self: ViewController {    var updateUITimer: NSTimer {     return NSTimer.scheduledTimerWithTimeInterval(updateInterval, target: self, selector: #selector(Self.updateUI(_:)), userInfo: nil, repeats: true)   }    func startUpdateUITimer() {     print(updateUITimer)   }    var updateInterval: NSTimeInterval {     return 60.0   } }