How do I perform a fast pixellation filter on an image?

Question

I have a little problem with my pixellation image processing algorithm.

I load the image from the beginning into an array of type unsigned char* After t

Answer 1

Converted @Kai Burghardt's answer to Swift 3

func pixelateImage(_ image: UIImage, withIntensity intensity: Int) -> UIImage {

    // initialize context and image
        let context = CIContext(options: nil)
        let logo = CIImage(data: UIImagePNGRepresentation(image)!)!
        // set filter and properties
        let filter = CIFilter(name: "CIPixellate")
        filter?.setValue(logo, forKey: kCIInputImageKey)
        filter?.setValue(CIVector(x:150,y:150), forKey: kCIInputCenterKey)
        filter?.setValue(intensity, forKey: kCIInputScaleKey)
        let result = filter?.value(forKey: kCIOutputImageKey) as! CIImage
        let extent = result.extent
        let cgImage = context.createCGImage(result, from: extent)
        // result
        let processedImage = UIImage(cgImage: cgImage!)
        return processedImage

}

calling this code as

self.myImageView.image =  pixelateImage(UIImage(named:"test"),100)