How to rotate image in Swift?

Question

I am unable to rotate the image by 90 degrees in swift. I have written below code but there is an error and doesn\'t compile

  func imageRotatedByDegrees(old         


        

Answer 1

Your code is not that far off from functional. You can apply the transform as you are doing directly to the bitmap, you don't need an intermediate view:

func imageRotatedByDegrees(oldImage: UIImage, deg degrees: CGFloat) -> UIImage {
    let size = oldImage.size

    UIGraphicsBeginImageContext(size)

    let bitmap: CGContext = UIGraphicsGetCurrentContext()!
    //Move the origin to the middle of the image so we will rotate and scale around the center.
    bitmap.translateBy(x: size.width / 2, y: size.height / 2)
    //Rotate the image context
    bitmap.rotate(by: (degrees * CGFloat(M_PI / 180)))
    //Now, draw the rotated/scaled image into the context
    bitmap.scaleBy(x: 1.0, y: -1.0)

    let origin = CGPoint(x: -size.width / 2, y: -size.width / 2)

    bitmap.draw(oldImage.cgImage!, in: CGRect(origin: origin, size: size))

    let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

Also, if you're going to create a function that rotates an image, it is typically good form to include a clockwise: Bool parameter that will interpret the degrees argument as rotating clockwise or not. The implementation and appropriate conversion to radians I leave to you.

Also note that it's a bit hand-wavy on my part to assume that oldImage.size is non-zero. If it is, force-unwrapping UIGraphicsGetCurrentContext()! will probably crash. You should validate the oldImage's size and if it's invalid just return oldImage.