manipulate pixel data by swift

gistfile1.swift

class BaseImageProcessor {

    func createARGBBitmapContext(imageRef : CGImageRef) -> CGContextRef! {
        var pixelWidth:UInt = CGImageGetWidth(imageRef);
        var pixelHeight:UInt = CGImageGetHeight(imageRef);
        var bitmapBytesPerRow:UInt = (pixelWidth * 4)
        var bitmapByteCount:UInt = (bitmapBytesPerRow * pixelHeight)
        
        var colorSpace:CGColorSpace = CGColorSpaceCreateDeviceRGB()
        
        var bitmapData:UnsafeMutablePointer<Void> = malloc(bitmapByteCount)
        if bitmapData == nil {
            return nil
        }
        
        var bitmapInfo = CGBitmapInfo.fromRaw(CGImageAlphaInfo.PremultipliedFirst.toRaw())!
        var context:CGContextRef = CGBitmapContextCreate(bitmapData, pixelWidth, pixelHeight, 8, bitmapBytesPerRow, colorSpace, bitmapInfo)
        return context
    }
    
    func manipulatePixel(imageRef : CGImageRef) -> UIImage? {
        var context = self.createARGBBitmapContext(imageRef)
        var width:Int  = Int(CGImageGetWidth(imageRef))
        var height:Int = Int(CGImageGetHeight(imageRef))
        var rect = CGRectMake(0, 0, CGFloat(width), CGFloat(height))
        
        CGContextDrawImage(context, rect, imageRef)
        
        var data: UnsafeMutablePointer<Void> = CGBitmapContextGetData(context)
        var dataType = UnsafeMutablePointer<UInt8>(data)
        
        var alpha, red, green, blue:UInt8
        var base, offset:Int
            
        for y in 0...(height - 1) {
                
            base = y * height * 4
            for x in 0...(width - 1) {

                offset = base + x * 4

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

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

        free(data)
        return newImage
    }
}