iOS Swift - 如何以编程方式为所有按钮分配默认操作

Question

我正在开发一个处于原型(prototype)开发阶段的应用程序。某些界面元素没有通过 Storyboard 或编程方式分配给它们的任何操作。

根据 UX 指南，我想在应用程序中找到这些“非事件”按钮，并让它们在测试期间点击时显示“功能不可用”警报。这可以通过扩展 UIButton 来完成吗？

除非通过界面生成器或以编程方式分配另一个 Action ，否则如何将默认 Action 分配给 UIButton 以显示警报？

Answer 1

好吧，您想要实现的目标是可以实现的。我使用 UIViewController 扩展并添加一个闭包作为没有目标的按钮的目标来完成此操作。如果按钮没有 Action ，则会显示警报。

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.checkButtonAction()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

    }
    @IBAction func btn_Action(_ sender: UIButton) {

    }

}

extension UIViewController{
    func checkButtonAction(){
        for view in self.view.subviews as [UIView] {
            if let btn = view as? UIButton {
                if (btn.allTargets.isEmpty){
                    btn.add(for: .touchUpInside, {
                        let alert = UIAlertController(title: "Test 3", message:"No selector", preferredStyle: UIAlertControllerStyle.alert)

                        // add an action (button)
                        alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))

                        // show the alert
                        self.present(alert, animated: true, completion: nil)
                    })
                }
            }
        }

    }
}
class ClosureSleeve {
    let closure: ()->()

    init (_ closure: @escaping ()->()) {
        self.closure = closure
    }

    @objc func invoke () {
        closure()
    }
}

extension UIControl {
    func add (for controlEvents: UIControlEvents, _ closure: @escaping ()->()) {
        let sleeve = ClosureSleeve(closure)
        addTarget(sleeve, action: #selector(ClosureSleeve.invoke), for: controlEvents)
        objc_setAssociatedObject(self, String(format: "[%d]", arc4random()), sleeve, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN)
    }
}

我已经测试过了。希望这可以帮助。快乐编码。