IOS拖动，轻拂或甩UIView [英] IOS drag, flick, or fling a UIView

问题描述

想知道我会如何触摸或甩空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，但是如何给他们重力/惯性。这是由IOS处理吗？

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

推荐答案

可以产生你所描述的模拟重力/惯性之王的效果通过轻松（启动快，结束缓慢）和轻松（启动缓慢，结束快速）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.

支持放宽和缓解在iOS中可用，所以我不认为你需要任何外部图书馆，也不需要努力工作（尽管你可以想像，你的效果需要很多微调）。

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).

这将使对象转换为给定位置的动画效果：

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 ，手势识别器将为您提供两个重要信息来计算最终位置：速度和翻译，它们分别表示对象被移动的速度和速度。

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（这将是您想要的对象动画，我猜）这样：

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];

然后处理您的处理程序中的动画：

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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