iOS 图片裁剪 + 旋转

staticfunc cropImage(_ image: UIImage, withRect rect: CGRect, angle: Double) -> UIImage? {

 // Creates a bitmap-based graphics context with rect size

 // and makes it the current context

 UIGraphicsBeginImageContext(rect.size)

 // Get current graphics context

 guard let context = UIGraphicsGetCurrentContext()else{returnnil }

 // Move context origin to rect center

 context.translateBy(x: rect.width /2, y: rect.height /2)

 // Convert angle to radian and rotate

 context.rotate(by: CGFloat(angle /180* M_PI))

 // Move context origin back (-rect.width / 2, -rect.height / 2)

 // and move opposite direction of rect origin (-rect.minX, -rect.minY)

 context.translateBy(x: -rect.width /2- rect.minX, y: -rect.height /2- rect.minY)

 // Draw image at context origin

 image.draw(at: .zero)

 // Get image

 let finalImage = UIGraphicsGetImageFromCurrentImageContext()

 // Removes the current bitmap-based graphics context from the top of the stack

 UIGraphicsEndImageContext()

 // Return image

 returnfinalImage

}