IOS 拖动、轻弹或轻弹 UIView [英] IOS drag, flick, or fling a UIView

问题描述

想知道我将如何轻弹或轻弹 UIView，例如 http://www.cardflick.co/ 或https://squareup.com/cardcase 演示视频.

Was wondering how I would go about flicking or flinging a UIView, such as http://www.cardflick.co/ or https://squareup.com/cardcase demo videos.

我知道如何拖动物品，但你如何赋予它们重力/惯性.这是IOS处理的吗?

I know how to drag items, but how do you give them gravity/inertia. Is this handled by IOS?

推荐答案

您所描述的模拟重力/惯性之王的那种效果可以通过缓出(开始快，结束慢)和缓入(开始慢，结束快)计时功能.

The kind of effects that you are describing as simulating a king of gravity/inertia can be produced by means of ease-out (start fast, end slow) and ease-in (start slow, end fast) timing functions.

iOS 中支持缓出和缓入，因此我认为您不需要任何外部库或努力工作(尽管您可以想象，您的效果需要大量微调).

Support for easing out and easing in is available in iOS, so I don't think you need any external library nor hard work (although, as you can imagine, your effect will need a lot of fine tuning).

这将动画对象平移到给定位置，并具有缓出效果:

This will animate the translation of an object to a given position with an ease-out effect:

 [UIView animateWithDuration:2.0 delay:0
         options:UIViewAnimationOptionCurveEaseOut
         animations:^ {
               self.image.center = finalPosition;
         }
         completion:NULL];
 }

如果您通过 UIPanGestureRecognizer 处理您的手势，手势识别器将为您提供两个重要信息来计算最终位置:velocity 和 translation，分别表示物体移动的速度和距离.

If you handle your gesture through a UIPanGestureRecognizer, the gesture recognizer will provide you with two important information to calculate the final position: velocity and translation, which represent respectively how fast and how much the object was moved.

您可以在视图中安装平移手势识别器(我猜这将是您想要动画的对象)，如下所示:

You can install a pan gesture recognizer in your view (this would be the object you would like to animate, I guess) like this:

    UIPanGestureRecognizer* panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanFrom:)];
    [yourView addGestureRecognizer:panGestureRecognizer];
            [panGestureRecognizer release];

然后在你的处理程序中处理动画:

And then handle the animation in your handler:

 - (void)handlePanFrom:(UIPanGestureRecognizer*)recognizer {

    CGPoint translation = [recognizer translationInView:recognizer.view];
    CGPoint velocity = [recognizer velocityInView:recognizer.view];

    if (recognizer.state == UIGestureRecognizerStateBegan) {    
    } else if (recognizer.state == UIGestureRecognizerStateChanged) {
        <track the movement>
    } else if (recognizer.state == UIGestureRecognizerStateEnded) {
        <animate to final position>
    }
 }

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