iOS Swift - 如何以编程方式为所有按钮指定默认操作

问题描述：

我正在开发原型阶段的应用程序。某些界面元素没有通过故事板或编程方式分配给它们的任何操作。

I'm working with an app in prototype stage of development. Some interface elements do not have any action assigned to them either through storyboard or programmatically.

根据UX准则，我想在应用程序中找到这些非活动按钮，并在测试期间点击时显示功能不可用警报。这可以通过UIButton的扩展来完成吗？

According to UX guidelines, I want to find these "inactive" buttons in app and have them display a "feature not available" alert when tapped during testing. Can this be done through an extension of UIButton?

除非通过界面构建器分配了另一个操作，否则如何为UIButton分配默认操作以显示警报以编程方式？

答

那么你想要实现的目标是什么。我使用 UIViewController 扩展并添加了一个闭包作为没有目标的按钮的目标。如果按钮没有动作，则会显示警报。

Well what you are trying to achieve can be done. I have done this using a UIViewController extension and adding a closure as the target of a button which does not have a target. In case the button does not have an action an alert is presented.

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。快乐的编码。

I have tested it. Hope this helps. Happy coding.

iOS Swift - 如何以编程方式为所有按钮指定默认操作

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