Convert UIImage to grayscale

ImageToGrayscale.swift

func convertImageToGrayScale(image: UIImage) -> UIImage {
    // Create image rectangle with current image width/height
    let imageRect = CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height)
    
    // Grayscale color space
    let colorSpace = CGColorSpaceCreateDeviceGray()
    
    // Create bitmap content with current image size and grayscale colorspace
    let context = CGContext(data: nil, width: Int(image.size.width), height: Int(image.size.height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: CGImageAlphaInfo.none.rawValue)!
    
    // Draw image into current context, with specified rectangle using previously defined context (with grayscale colorspace)
    context.draw(image.CGImage, in: imageRect)
    
    // Create bitmap image info from pixel data in current context
    let imageRef = context.makeImage()!
    
    // Create a new UIImage object
    let newImage: UIImage = UIImage(CGImage: imageRef)!
    
    // Return the new grayscale image
    return newImage
}