创建一个继承自 UITouch 的类

Question

我正在使用 Swift 3 和 Xcode

我有以下课程：

class Finger: UITouch
{
    var firstTimeStamp: TimeInterval = 0.0
}

还有这个变量：

var finger: Finger?

这是我的touchesBegan 函数：

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)
{
    if finger == nil
    {
        let touch = touches.first
        finger = touch as! GameScene.Finger?    <--- ERROR
        finger?.firstTimeStamp = finger!.timestamp
    }
}

它可以构建，但是当我触摸屏幕时出现此错误： Could not cast value of type 'UITouch' (0x10f3b1ca8) to 'Project.GameScene.Finger' (0x10c3f71a0).

我想知道手指在屏幕上的时间，从 touchesBegan 到 touchesEnded。这是最好的方法吗？ 无论如何，我做错了什么？

Answer 1

我在 UIViewController 中插入下面的代码。

方式 1

var touchBeginDate:Date?

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    print("touchesBegan")
    if touchBeginDate == nil {
        touchBeginDate = Date()
    }
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

    if let touchBeginDate = touchBeginDate {

        let calendar = Calendar.current
        let components = calendar.dateComponents([Calendar.Component.second, Calendar.Component.minute], from: touchBeginDate, to: Date())
        print("\(components)")
    }

    touchBeginDate = nil
    print("touchesEnded")
}

结果

方式 2

class TapGestureRecognizer: UILongPressGestureRecognizer {
    var touchBeginDate:Date?
}

class ViewController: UIViewController, UIGestureRecognizerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        let tapGestureRecognizer = TapGestureRecognizer(target: self, action: #selector(ViewController.action(tapGestureRecognizer:)))
        tapGestureRecognizer.delegate = self
        tapGestureRecognizer.delaysTouchesBegan = false
        tapGestureRecognizer.delaysTouchesEnded = false
        view.addGestureRecognizer(tapGestureRecognizer)
    }

    func action(tapGestureRecognizer: TapGestureRecognizer) {
        switch tapGestureRecognizer.state {
        case .began:
            print("touch began")
            if tapGestureRecognizer.touchBeginDate == nil {
                tapGestureRecognizer.touchBeginDate = Date()
            }
        case .ended:
            if let touchBeginDate = tapGestureRecognizer.touchBeginDate {
                let calendar = Calendar.current
                let components = calendar.dateComponents([Calendar.Component.second, Calendar.Component.minute], from: touchBeginDate, to: Date())
                print("\(components)")
            }
            tapGestureRecognizer.touchBeginDate = nil
            print("touch ended")
        case .cancelled:
            break
        case .failed:
            break
        case .possible:
            break
        case .changed:
            break
        }
    }
}