UIGestureRecognizer + Closure extenstion

UIGestureRecognizerClosure.swift

extension UIGestureRecognizer {
    
    private class TargetAndSelector: NSObject {
        let closure: UIGestureRecognizer -> Void
        let recognizer: UIGestureRecognizer
        
        init(recognizer: UIGestureRecognizer, closure: UIGestureRecognizer -> Void) {
            self.recognizer = recognizer
            self.closure = closure
        }
        
        @objc func invoke() {
            self.closure(self.recognizer)
        }
    }
    
    
    convenience init(closure: UIGestureRecognizer -> Void) {
        self.init()
        
        let handler = TargetAndSelector(recognizer: self, closure: closure)
        self.addTarget(handler, action: "invoke")
        
        objc_setAssociatedObject(self, "_closure", handler, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
}