旋转瓶与UIGestureRecognizer

Question

我现在使用此代码在按钮水龙头上旋转瓶子:

@IBAction func spinButton(sender: AnyObject) {
        let rotateView = CABasicAnimation()
        let randonAngle = arc4random_uniform(360) + 720
        rotateView.fromValue = 0
        rotateView.toValue = Float(randonAngle) * Float(M_PI) / 180.0
        rotateView.duration = 3
        rotateView.delegate = self
        rotateView.repeatCount = 0
        rotateView.removedOnCompletion = false
        rotateView.fillMode = kCAFillModeForwards
        rotateView.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
        bottleImageView.layer.addAnimation(rotateView, forKey: "transform.rotation.z")
    }

但是如何使用手势旋转按钮？因此,我移动手指越硬/越快,瓶子旋转的速度就越快

Answer 1

对此的简单答案是......使用UIScrollView.

从我的问题来看......循环 UIScrollView 但继续减速

将其转换为 Swift 很简单，但这里是......

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    //make the content size really big so that the targetOffset of the deceleration will never be met.

    scrollView.contentSize = CGSize(width: CGRectGetWidth(scrollView.frame) * 100.0, height: CGRectGetHeight(scrollView.frame))
    //set the contentOffset of the scroll view to a point in the center of the contentSize.
    scrollView.setContentOffset(CGPoint(CGRectGetWidth(scrollView.frame) * 50, 0), animated: false)
}

func rotateImageView() {
    //Calculate the percentage of one "frame" that is the current offset.

    // each percentage of a "frame" equates to a percentage of 2 PI Rads to rotate
    let minOffset = CGRectGetWidth(scrollView.frame) * 50.0
    let maxOffset = CGRectGetWidth(scrollView.frame) * 51.0

    let offsetDiff = maxOffset - minOffset

    let currentOffset = scrollView.contentOffset.x - minOffset

    let percentage = currentOffset / offsetDiff

    arrowView.transform = CGAffineTransformMakeRotation(M_PI * 2 * percentage)
}

func scrollViewDidScroll(scrollView: UIScrollView) {
    //the scrollView moved so update the rotation of the image
    rotateImageView()
}

func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
    //the scrollview stopped moving.
    //set the content offset back to be in the middle
    //but make sure to keep the percentage (used above) the same
    //this ensures the arrow is pointing in the same direction as it ended decelerating

    let diffOffset = scrollView.contentOffset.x

    while diffOffset >= CGRectGetWidth(scrollView.frame) {
        diffOffset = diffOffset - CGRectGetWidth(scrollView.frame)
    }

    scrollView.setContentOffset(CGPoint(x: CGRectGetWidth(scrollView.frame) * 50 + diffOffset, y: 0), animated:false)
}

在这个例子中，我的旋转视图是arrowView. 和scrollView都arrowView应该是视图控制器视图的子视图。scrollView里面不应该有任何东西。

注意这是在浏览器中完成的，因此可能存在一些语法问题。您可能还需要将一些数字转换为CGFloat等等......

此外，能够从 Objective-C 进行翻译对于任何 iOS 开发人员来说都是至关重要的。数以百万计的应用程序是使用 Objective-C 编写的。语法可能略有不同，但所有 API 都是相同的。

学习如何做到这一点是每个 iOS 开发人员都应该做的事情。