UIControl.swift - Adds a closure based target/action support to all UIControl based components, including basic lifecycle handling

UIControl.swift

public protocol ClosureActionable: class {
    func addTarget(target: AnyObject, forControlEvents controlEvents: UIControlEvents, closure: (Self) -> Void) -> AnyObject
    func removeTarget(pointer: AnyObject)
}
extension UIControl: ClosureActionable { }

public extension ClosureActionable where Self: UIControl {
    private var pointers: [TargetPointer] {
        get {
            if let existing = objc_getAssociatedObject(self, ClosureAssociatedKeys.Pointers) as? [TargetPointer] { return existing }
            self.pointers = []
            return self.pointers
        }
        set {
            objc_setAssociatedObject(self, ClosureAssociatedKeys.Pointers, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        }
    }

    public func addTarget(target: AnyObject, forControlEvents controlEvents: UIControlEvents, closure: (Self) -> Void) -> AnyObject {
        let pointer = TargetPointer(self, target: target, controlEvents: controlEvents) {
            if let _ = $0.target { closure(self) }
            else { self.removeTarget($0) }
        }
        self.pointers.append(pointer)
        self.addTarget(pointer, action: "actionTriggered", forControlEvents: controlEvents)
        return pointer
    }
    public func removeTarget(pointer: AnyObject) {
        guard let pointer = pointer as? TargetPointer else { return }
        
        self.removeTarget(pointer, action: "actionTriggered", forControlEvents: pointer.controlEvents)
    }
}

private struct ClosureAssociatedKeys {
    static var Pointers = "Pointers"
}
private class TargetPointer: NSObject {
    weak var target: AnyObject?
    let controlEvents: UIControlEvents
    private let closure: (TargetPointer) -> Void
    
    init(_ control: UIControl, target: AnyObject, controlEvents: UIControlEvents, closure: (TargetPointer) -> Void) {
        self.target = target
        self.controlEvents = controlEvents
        self.closure = closure
    }
    @objc private func actionTriggered() { self.closure(self) }
}

Usage.swift

let pointer = button.addTarget(target, forControlEvents: .TouchUpInside) { btn in
    //..
}

/* either of the following two things would stop the closure from being fired  */
target = nil 
button.removeTarget(pointer)