如何在Swift中控制动画旋转方向超过180 °？

cnwbcb6i 于 2023-02-15 发布在 Swift

关注(0)|答案(4)|浏览(163)

根据rotated(by:)的文档：
角
旋转仿射变换的Angular （以弧度为单位）。在iOS中，正值指定逆时针旋转，负值指定顺时针旋转。
这引起了很多混乱，并且已经得到了部分解答，但是即使我们接受坐标系被翻转（并且只是按照文档所述的相反操作），在设置动画时仍然会提供不一致的结果。
旋转方向（顺时针或逆时针）取决于目标旋转与当前旋转的接近程度：

<= 180º顺时针设置动画
> 180º逆时针设置动画

使用UIView.animate或UIViewPropertyAnimator显示不一致：

// Animates CLOCKWISE
UIView.animate(withDuration: 2.0) {
    let radians = Angle(179).radians // 3.12413936106985
    view.transform = view.transform.rotated(by: CGFloat(radians))
}
// Animates COUNTER-CLOCKWISE
UIViewPropertyAnimator(duration: 2, curve: .linear) {
    let radians = Angle(181).radians // 3.15904594610974
    view.transform = view.transform.rotated(by: CGFloat(radians))
}
// Does not animate
UIViewPropertyAnimator(duration: 2, curve: .linear) {
    let radians = Angle(360).radians // 6.28318530717959
    view.transform = view.transform.rotated(by: CGFloat(radians))
}

swift

来源：https://stackoverflow.com/questions/41182386/how-to-control-animation-rotation-direction-in-swift-past-180%c2%ba

4条答案

按热度按时间

iezvtpos1#

试试这个：

let multiplier: Double = isSelected ? 1 : -2
    let angle = CGFloat(multiplier * Double.pi)

    UIView.animate(withDuration: 0.4) {
        self.indicatorImageView.transform = CGAffineTransform(rotationAngle: angle)
    }

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wrrgggsh2#

答案是使用CABasicAnimation表示超过180 °的旋转，记住 * 正值表示顺时针，负值表示逆时针 *。

// Rotate 360º clockwise.
let rotate = CABasicAnimation(keyPath: "transform.rotation")
rotate.fromValue = Angle(0).radians
rotate.toValue = Angle(360).radians
rotate.duration = 2.0
self.layer.add(rotate, forKey: "transform.rotation")

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w46czmvw3#

if sender.isSelected {
        /// clockwise
        let rotate = CABasicAnimation(keyPath: "transform.rotation")
        rotate.fromValue = 0
        rotate.toValue = CGFloat.pi
        rotate.duration = 0.25
        rotate.fillMode = CAMediaTimingFillMode.forwards
        rotate.isRemovedOnCompletion = false
        self.arrowButton.layer.add(rotate, forKey: "transform.rotation")
    } else {
        /// anticlockwise
        let rotate = CABasicAnimation(keyPath: "transform.rotation")
        rotate.fromValue = CGFloat.pi
        rotate.toValue = 0
        rotate.duration = 0.25
        rotate.fillMode = CAMediaTimingFillMode.forwards
        rotate.isRemovedOnCompletion = false
        self.arrowButton.layer.add(rotate, forKey: "transform.rotation")
    }

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gojuced74#

第三个选项允许您在所需方向上旋转180º：

// #1 This rotates 90º clockwise
        UIView.animate(withDuration: 0.25, animations:{
            view.transform = CGAffineTransform(rotationAngle: -CGFloat.pi/2)
        })
        
        // #2 This rotates 90º counter clockwise back to #1
        UIView.animate(withDuration: 0.25, animations:{
            view.transform = CGAffineTransform(rotationAngle: CGFloat.pi)
        })
        
        // #3 This rotates 270º clockwise back to #1
        UIView.animate(withDuration: 0.1875, animations:{
            view.transform = CGAffineTransform(rotationAngle: CGFloat.pi/2)
        }, completion: { _ in
            UIView.animate(withDuration: 0.0625, animations:{
                view.transform = CGAffineTransform(rotationAngle: CGFloat.pi)
            })
        })

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如何在Swift中控制动画旋转方向超过180 °？

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