Manipulate pixel data in swift 3.0

gistfile1.swift

class BaseImageProcessor {

    func createARGBBitmapContext(image: CGImage) -> CGContext? {
        let pixelWidth = image.width
        let pixelHeight = image.height
        let bitmapBytesPerRow = pixelWidth * 4
        let bitmapByteCount = bitmapBytesPerRow * pixelHeight
        let bitmapData: UnsafeMutableRawPointer = malloc(bitmapByteCount)
        
        let colorSpace: CGColorSpace = CGColorSpaceCreateDeviceRGB()
        guard let bitmapContext = CGContext(data: bitmapData,
                                            width: pixelWidth,
                                            height: pixelHeight,
                                            bitsPerComponent: 8,
                                            bytesPerRow: bitmapBytesPerRow,
                                            space: colorSpace,
                                            bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue) else {
                                                return nil
        }
        return bitmapContext
    }
    
    func manipulatePixel(of image: CGImage) -> UIImage? {
        
        guard let context = createARGBBitmapContext(image: image) else {
            return nil
        }
        let width = context.width
        let height = context.height
        var rect = CGRect(x: 0, y: 0, width: width, height: height)

        CGContextDrawImage(context, rect, image)
        
        guard let pixelData = image.dataProvider?.data else {
            return nil
        }
        let pixelBuffer: UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData)
        
        var alpha, red, green, blue: UInt8
        var base, offset:Int
            
        for y in 0...(height - 1) {
                
            base = y * width * 4
            for x in 0...(width - 1) {

                offset = base + x * 4

                alpha = pixelBuffer[offset]
                red   = pixelBuffer[offset + 1]
                green = pixelBuffer[offset + 2]
                blue  = pixelBuffer[offset + 3]
            }
        }

        var imageRef = CGBitmapContextCreateImage(context);
        var newImage = UIImage(CGImage: imageRef)

        return newImage
    }
}

Warning, this code will not yet work on swift 3.0 (Especially the newImage creation is not converted and checked)