这是我在查看其他人编写的几个旧代码后编写的UIImage扩展。它使用Swift 3编写,并使用iOS方向属性加上CGAffineTransform以正确方向重新绘制图像。
SWIFT 3:
public extension UIImage {
func fixOrientation() -> UIImage {
guard let cgImage = cgImage else { return self }
if imageOrientation == .up { return self }
var transform = CGAffineTransform.identity
switch imageOrientation {
case .down, .downMirrored:
transform = transform.translatedBy(x: size.width, y: size.height)
transform = transform.rotated(by: CGFloat(M_PI))
case .left, .leftMirrored:
transform = transform.translatedBy(x: size.width, y: 0)
transform = transform.rotated(by: CGFloat(M_PI_2))
case .right, .rightMirrored:
transform = transform.translatedBy(x: 0, y: size.height)
transform = transform.rotated(by: CGFloat(-M_PI_2))
case .up, .upMirrored:
break
}
switch imageOrientation {
case .upMirrored, .downMirrored:
transform.translatedBy(x: size.width, y: 0)
transform.scaledBy(x: -1, y: 1)
case .leftMirrored, .rightMirrored:
transform.translatedBy(x: size.height, y: 0)
transform.scaledBy(x: -1, y: 1)
case .up, .down, .left, .right:
break
}
if let ctx = CGContext(data: nil, width: Int(size.width), height: Int(size.height), bitsPerComponent: cgImage.bitsPerComponent, bytesPerRow: 0, space: cgImage.colorSpace!, bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue) {
ctx.concatenate(transform)
switch imageOrientation {
case .left, .leftMirrored, .right, .rightMirrored:
ctx.draw(cgImage, in: CGRect(x: 0, y: 0, width: size.height, height: size.width))
default:
ctx.draw(cgImage, in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
}
if let finalImage = ctx.makeImage() {
return (UIImage(cgImage: finalImage))
}
}
return self
}
}