TargetActionClosureAdapter

TargetActionClosureAdapter.swift

import UIKit
import ObjectiveC.runtime

private class TargetActionClosureAdapter<T : AnyObject> {
    
    typealias Closure = (sender: T!) -> Void
    
    private let closure: Closure
    
    private init() {
        closure = {_ in }
    }
    
    init(_ closure: Closure) {
        self.closure = closure
    }
    
    var actionSelector: Selector {
        return #selector(self.dynamicType.action(_:))
    }
    
    @objc
    private func action(sender: AnyObject) {
        closure(sender: sender as? T)
    }
}

private var associatedObjectKey: Int = 0

private extension TargetActionClosureAdapter {
    private func attachToObject(object: AnyObject) {
        objc_setAssociatedObject(object, &associatedObjectKey, self, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
}

public extension UIControl {
    @objc(sgv_addHandlerForControlEvents:withBlock:)
    public func addHandlerForControlEvents(controlEvents: UIControlEvents, handler: (sender: UIControl!) -> Void) {
        let adapter = TargetActionClosureAdapter(handler)
        addTarget(adapter, action: adapter.actionSelector, forControlEvents: controlEvents)
        adapter.attachToObject(self)
    }
}

public extension UIBarButtonItem {
    @objc(sgv_addHandlerWithBlock:)
    public func addHandler(handler: (sender: UIBarButtonItem!) -> Void) {
        let adapter = TargetActionClosureAdapter(handler)
        target = adapter
        action = adapter.actionSelector
        adapter.attachToObject(self)
    }
}

public extension UIAccessibilityCustomAction {
    @objc(sgv_addHandlerWithBlock:)
    public func addHandler(handler: (sender: UIAccessibilityCustomAction!) -> Void) {
        let adapter = TargetActionClosureAdapter(handler)
        target = adapter
        selector = adapter.actionSelector
        adapter.attachToObject(self)
    }
}

public extension UIGestureRecognizer {
    @objc(sgv_addHandlerWithBlock:)
    public func addHandler(handler: (sender: UIGestureRecognizer!) -> Void) {
        let adapter = TargetActionClosureAdapter(handler)
        addTarget(adapter, action: adapter.actionSelector)
        adapter.attachToObject(self)
    }
}

public extension CADisplayLink {
    @objc(sgv_initWithHandlerBlock:)
    public convenience init(handler: (sender: CADisplayLink!) -> Void) {
        let adapter = TargetActionClosureAdapter(handler)
        self.init(target: adapter, selector: adapter.actionSelector)
    }
}