如何在 .Ended 状态下访问 Pan Gesture 的初始点

Question

我正在尝试在我的应用程序中实现一个平移手势，我需要访问处于 .Ended 状态的初始点。

这是代码。

func handleTestViewTap (panRecognizer: UIPanGestureRecognizer){

    var locationOfBeganTap: CGPoint?

    if panRecognizer.state == UIGestureRecognizerState.Began {           
        locationOfBeganTap = panRecognizer.locationInView(view)
        print("locationOfBeganTap in BEGAN State -> .\(locationOfBeganTap)")

    } else if panRecognizer.state == UIGestureRecognizerState.Ended {            
        print("locationOfBeganTap -> .\(locationOfBeganTap)")
        print("locationOfBeganTap in ENDED State -> .\(locationOfBeganTap)")

    }     
}

现在，这是输出：

locationOfBeganTap in BEGAN State -> .Optional((195.5, 120.0))
locationOfBeganTap in ENDED State -> .nil

我无法理解为什么 locationOfBeganTap 处于 .Ended 状态 nil

有人可以分享代码以在 .Ended 状态下访问 locationOfBeganTap...

Answer 1

您需要将 locationOfBeganTap 移动为实例变量而不是局部变量。

class WhatEverClassThisIs {
    var locationOfBeganTap: CGPoint?

    // and the rest of your stuff

    func handleTestViewTap (panRecognizer: UIPanGestureRecognizer){
        if panRecognizer.state == UIGestureRecognizerState.Began {           
            locationOfBeganTap = panRecognizer.locationInView(view)
            print("locationOfBeganTap in BEGAN State -> .\(locationOfBeganTap)")
        } else if panRecognizer.state == UIGestureRecognizerState.Ended {            
            print("locationOfBeganTap -> .\(locationOfBeganTap)")
            print("locationOfBeganTap in ENDED State -> .\(locationOfBeganTap)")
        }     
    }
}

Answer 2

你这样做的方式行不通。相反，在最后计算它：

func handleTestViewTap (panRecognizer: UIPanGestureRecognizer){

    if panRecognizer.state == UIGestureRecognizerState.Ended {            
        print("locationOfBeganTap -> (.\(touch.locationInView(view).x - touch.translationInView(view).x), .\(touch.locationInView(view).y - touch.translationInView(view).y))")
        print("location in ENDED State -> .\(touch.locationInView(view))")
    }     
}

如何在 .Ended 状态下访问 Pan Gesture 的初始点

How to access the initial point of a Pan Gesture in it's .Ended state

uigesturerecognizer

cgpoint

ios

uipangesturerecognizer

swift