iOS SDK Core Graphics 游戏对象旋转？

Question

如何在核心图形中旋转矩形或圆形等对象？是否可以使用核心动画来做到这一点？

Answer 1

尝试设置视图的变换属性（可设置动画）或使用 CGAffineTransformMakeRotation 进行变换，以便在绘图时应用于上下文。

Answer 2

extension Double {
    var degreesToRadians: CGFloat {
        return CGFloat(self) * CGFloat(M_PI) / CGFloat(180.0)
    }
}
class Rectangle: UIView {
    override func draw(_ rect: CGRect) {
        let context = UIGraphicsGetCurrentContext()
        let path = UIBezierPath(rect: rect.insetBy(dx: 90, dy: 100))
        context?.translateBy(x: rect.midX, y: -100)
        context?.rotate(by: 45.0.degreesToRadians)
        context?.setStrokeColor(UIColor.green.cgColor)
        context?.setLineWidth(5.0)
        context?.addPath(path.cgPath)
        context?.strokePath()
    }
}

添加动画

class Rectangle: UIView {
        override func draw(_ rect: CGRect) {
            let path = UIBezierPath(rect: rect.insetBy(dx: 90, dy: 100))

            // Add shape layer
            let rectangle = CAShapeLayer()
            rectangle.frame = bounds
            rectangle.path = path.cgPath
            rectangle.strokeColor = UIColor.yellow.cgColor
            layer.addSublayer(rectangle)

            // create transform
            let transform = CATransform3DMakeRotation(90.0.degreesToRadians, 0, 0, 1)

            // Animate the transform
            let anim = CABasicAnimation(keyPath: "transform.rotation.z")
            anim.fromValue = CATransform3DIdentity
            anim.toValue = transform
            anim.duration = 2.0
            anim.repeatCount = Float.infinity
            layer.add(anim, forKey: nil)
        }
    }