如何减慢UIPanGestureRecognizer的速度？

Question

我有一个方法，当识别到 2 指平移手势时，我想调用该方法。我已经设置好并且工作正常，但问题是我只需要大约 15 次调用该方法（它过滤图像），当我平移大约一英寸时，该方法已被调用一百遍，图像转得如此之快，我不知道发生了什么。

我该怎么做才能减慢手势识别器的速度？

UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(move:)];
[panRecognizer setMinimumNumberOfTouches:2];
[panRecognizer setMaximumNumberOfTouches:2];
[panRecognizer setDelegate:self];
[self view] addGestureRecognizer:panRecognizer]];

Answer 1

想必您每次收到平移事件时都会更改图像。这不太好。相反，您应该向平移手势识别器询问拖动距离（使用 -translationInView:），并且仅在超过特定阈值后才更改图像。

Answer 2

我创建了一个“responseCount”，基本上捕获每第四个或第五个（有效）手势。

// within method that fires with each gesture:
CGPoint translatedPoint = [(UIPanGestureRecognizer*)panRecognizer translationInView:aView];
if(abs(translatedPoint.x) > 20 || abs(translatedPoint.y) > 20){
    if(responseCount == 4){
        // do animation/response
        responseCount = 0;
    } else {
        responseCount += 1;
    }
}

Answer 3

斯威夫特4

@objc func panGestureHandler(_ gesture: UIPanGestureRecognizer) {

    let theViewMinimumY = someValue
    let translation = gesture.translation(in: gesture.view)

    switch gesture.state {

    case .began:
        gesture.setTranslation(CGPoint.zero, in: gesture.view)

    case .changed:

        gesture.setTranslation(CGPoint.zero, in: gesture.view)

        // if the view ever goes beyond a certain point
        if theView.frame.origin.y < theViewMinimumY {

            // only add a fraction of the gesture's translation (in this case 50%)
            theView.center = CGPoint(x: theView.center.x, y: theView.center.y + (translation.y * 0.5))

        } else {

            theView.center = CGPoint(x: theView.center.x, y: theView.center.y + translation.y)

        }

    case .ended:

        ...

    default:
        break

    }

}