Question

我有一个简单的ViewController，中间有一个View，当我添加UITapGestureRecognizer时，它将正常运行，但是当我从外部类尝试相同的操作时，它将不起作用（从未调用该方法）。我的问题是

我需要对Listener类进行哪些更改以使其调用其中的方法

以下是代码：

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var myView: UIView!

    override func viewDidLoad() {
        super.viewDidLoad()
        Listener(view : view , viewController: self).listen()
    }

    @objc func onNewTabArrived(){
        print("Hello from inside the controller")
    }

}


class Listener {
    let view : UIView
    let viewController: UIViewController

    init(view : UIView , viewController: UIViewController){
        self.view  = view
        self.viewController  = viewController
    }
    func listen(){
        // If you set the target as viewController it will call the method named onNewTabArrived inside it , printing "Hello from inside the controller"
        // let tab = UITapGestureRecognizer(target: viewController, action: #selector(onNewTabArrived))
        // view.addGestureRecognizer(tab)


        // This will not work! the text "Hello from inside Listener" will never be printed, How can I force it to be called ?.
         let tab = UITapGestureRecognizer(target: self, action: #selector(onNewTabArrived))
         view.addGestureRecognizer(tab)
    }

    @objc func onNewTabArrived(){
        print("Hello from inside Listener")
    }

}

Answer 1

您的Listener对象在创建后即被释放。尝试将其存储到属性中

@IBOutlet weak var myView: UIView!
var listener: Listener?
override func viewDidLoad() {
    super.viewDidLoad()
    self.listener = Listener(view : view , viewController: self)
    self.listener?.listen()
}

如果目标是普通类，则UITapGestureRecognizer无法正常工作

1 个答案: