如何围绕左上角的点旋转图像？

Question

我有一个音乐播放器，我想在玩家正在播放时，图像在磁盘上。当播放器没有播放时，将图像围绕左上角的点旋转45°.heckImgView的约束为centerX to superView, top to superview = 40, size = (97,153)

我用Google搜索并找到以下代码：

func setAnchorPoint(_ anchorPoint:CGPoint, for view:UIView){

        let oldOrigin = view.frame.origin
        view.layer.anchorPoint = anchorPoint
        let newOrigin = view.frame.origin

        var transition = CGPoint()
        transition.x = newOrigin.x - oldOrigin.x
        transition.y = newOrigin.y - oldOrigin.y
        view.center = CGPoint(x: view.center.x - transition.x, y: view.center.y - transition.y)

    }

使用以下方法旋转图像：

if !player.isPlaying {
        setAnchorPoint(CGPoint(x:40 / 97.0,y:40 / 153.0), for: needleImgView) // I'm NOT SURE the 40 is right.
        //needleImgView.layer.anchorPoint = CGPoint(x:0,y:0)
        UIView.animate(withDuration: 0.5, animations: {
            self.needleImgView.transform = CGAffineTransform(rotationAngle: CGFloat(-Double.pi / 4))
        }, completion: nil)

    }else{
        setAnchorPoint(CGPoint(x:40 / 97.0,y:40 / 153.0), for: needleImgView) 
        //needleImgView.layer.anchorPoint = CGPoint(x:0,y:0)
        UIView.animate(withDuration: 0.5, animations: {
            self.needleImgView.transform = .identity
        }, completion: nil)

    }

我设置setAnchorPoint(CGPoint(x:0 / 97.0,y:0 / 153.0), for: needleImgView)或needleImgView.layer.anchorPoint = CGPoint(x:0,y:0)，结果是左上角点也移开。

  

如何解决？ THX。

Answer 1

有两种方法可以解决它---

1-您必须按40更改0。

setAnchorPoint(CGPoint(x:0 / 97.0,y:0 / 153.0), for: needleImgView);

更改守则----

setAnchorPoint(CGPoint(x:-10.0 / 97.0,y:0 / 153.0), for: YourImage)

为图片制作相同更改X中的值。

2-拍摄双倍大小的图像像时钟一样，你的指针将从中间开始像钟针一样，你可以在没有锚点的情况下旋转。但这是解决的坏方法。

先尝试一下。它会帮助你，或者让你感到自由。

Answer 2

您可以尝试CABasicAnimation。

0.5 x的锚点意味着在宽度的中间，0的y意味着在高度的顶部。

    imageView.layer.anchorPoint = CGPoint.init(x: 0.5, y: 0)

    let basic = CABasicAnimation.init(keyPath: "transform.rotation")
    basic.fromValue = NSNumber.init(value: 0)
    basic.toValue = NSNumber.init(value: -(Double.pi / 4))
    basic.fillMode = kCAFillModeForwards
    basic.isRemovedOnCompletion = false
    imageView.layer.add(basic, forKey: nil)