ios - 以编程方式为所有 UISlider 分配默认操作

Question

我的应用程序处于开发原型(prototype)阶段。有些 slider 没有通过 Storyboard 或编程方式分配给它们任何操作。

我需要在测试期间 slider 拖动停止时显示警告。这可以通过 UISlider 的扩展来完成吗？

当拖动结束以显示警报时，我如何将默认操作分配给 UISlider，除非通过界面生成器或以编程方式分配另一个操作？

Similar Question

Answer 1

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)

}

}

extension UIViewController{
    func checkButtonAction(){
        for view in self.view.subviews as [UIView] {
            if let btn = view as? UISlider {
                if (btn.allTargets.isEmpty){
                    btn.add(for: .allTouchEvents, {
                        if (!btn.isTracking){
                            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)
    }
}

请检查这个修改后的答案。