image rotation to swift

  func fixedOrientation() -> UIImage {

    if imageOrientation == UIImageOrientation.Up {
      return self
    }

    var transform: CGAffineTransform = CGAffineTransformIdentity

    switch imageOrientation {
    case UIImageOrientation.Down, UIImageOrientation.DownMirrored:
      transform = CGAffineTransformTranslate(transform, size.width, size.height)
      transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
      break
    case UIImageOrientation.Left, UIImageOrientation.LeftMirrored:
      transform = CGAffineTransformTranslate(transform, size.width, 0)
      transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2))
      break
    case UIImageOrientation.Right, UIImageOrientation.RightMirrored:
      transform = CGAffineTransformTranslate(transform, 0, size.height)
      transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))
      break
    case UIImageOrientation.Up, UIImageOrientation.UpMirrored:
      break
    }

    switch imageOrientation {
    case UIImageOrientation.UpMirrored, UIImageOrientation.DownMirrored:
      CGAffineTransformTranslate(transform, size.width, 0)
      CGAffineTransformScale(transform, -1, 1)
      break
    case UIImageOrientation.LeftMirrored, UIImageOrientation.RightMirrored:
      CGAffineTransformTranslate(transform, size.height, 0)
      CGAffineTransformScale(transform, -1, 1)
    case UIImageOrientation.Up, UIImageOrientation.Down, UIImageOrientation.Left, UIImageOrientation.Right:
      break
    }

    let ctx: CGContextRef = CGBitmapContextCreate(nil, Int(size.width), Int(size.height), CGImageGetBitsPerComponent(CGImage!), 0, CGImageGetColorSpace(CGImage!)!, CGImageAlphaInfo.PremultipliedLast.rawValue)!

    CGContextConcatCTM(ctx, transform)

    switch imageOrientation {
    case UIImageOrientation.Left, UIImageOrientation.LeftMirrored, UIImageOrientation.Right, UIImageOrientation.RightMirrored:
      CGContextDrawImage(ctx, CGRectMake(0, 0, size.height, size.width), CGImage!)
      break
    default:
      CGContextDrawImage(ctx, CGRectMake(0, 0, size.width, size.height), CGImage!)
      break
    }

    let cgImage: CGImageRef = CGBitmapContextCreateImage(ctx)!

    return UIImage(CGImage: cgImage)
  }