How to change UIImage color? - ios

Question

I'd like to change the color of every pixel of any UIImage to a specific color (all pixel should get the same color):
... so of course I could just loop trough every pixel of the UIImage and set it's red, green and blue property to 0 to achieve a black-color look.
But obviously this is not a effective way to recolor an image and I'm pretty sure there are several more effective methods achieving this instead of looping trough EVERY single pixel of the image.
func recolorImage(image: UIImage, color: String) -> UIImage {
let img: CGImage = image.cgImage!
let context = CGContext(data: nil, width: img.width, height: img.height, bitsPerComponent: 8, bytesPerRow: 4 * img.width, space: CGColorSpaceCreateDeviceRGB(), bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)!
context.draw(img, in: CGRect(x: 0, y: 0, width: img.width, height: img.height))
let data = context.data!.assumingMemoryBound(to: UInt8.self)
for i in 0..<img.height {
for j in 0..<img.width {
// set data[pixel] ==> [0,0,0,255]
}
}
let output = context.makeImage()!
return UIImage(cgImage: output)
}
Ayn help would be very appreciated!

Answer 1

Since every pixel of the original image will be the same color, the result image is not dependent on the pixels of the original image. Your method actually just needs the size of the image and then creates a new image with that size, that is filled with one single color.
func recolorImage(image: UIImage, color: UIColor) -> UIImage {
let size = image.size
UIGraphicsBeginImageContext(size)
color.setFill()
UIRectFill(CGRect(origin: .zero, size: size))
let image = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return image
}