Fill color on specific part of image in ios Swift 3.0

I am working on a color application. In which the application has an image, and we have to paint it with the selected color.

I am trying a lot to complete the application. But still, don't get the perfect way to fill color in a specific part of the image.

I am trying to get the color of a pixel using this code.

func getPixelColor(pos: CGPoint) -> UIColor {

        let pixelData = self.cgImage!.dataProvider!.data
        let data: UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData)

        let pixelInfo: Int = ((Int(self.size.width) * Int(pos.y)) + Int(pos.x)) * 4

        let r = CGFloat(data[pixelInfo]) / CGFloat(255.0)
        let g = CGFloat(data[pixelInfo+1]) / CGFloat(255.0)
        let b = CGFloat(data[pixelInfo+2]) / CGFloat(255.0)
        let a = CGFloat(data[pixelInfo+3]) / CGFloat(255.0)

        return UIColor(red: r, green: g, blue: b, alpha: a)
}

      

        
        
        
      

    

The higher the running code, the more it determines the color of the pixel.

But after the code above, try to fill the color on a specific part of the image touch.

Flood Algo is also used, but it does not completely fill the specific part.

Tried Masking method to fill a specific part of the image.

I am using below code to fill color on touch pixel as shown in picture above. You see a red color that shows the location of the touch and changes the color of that pixel to red.

 UIGraphicsBeginImageContextWithOptions((rect?.size)!, false, (images?.scale)!)
        let c = UIGraphicsGetCurrentContext()
        images?.draw(in: rect!)

        c!.setFillColor(UIColor.red.cgColor)
        c!.setBlendMode(CGBlendMode.normal)


        c!.fill(CGRect(x: (location?.x)!, y: (location?.y)!, width: 10, height:10))

         let result = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        img.image = result

      

        
        
        
      

    

Anyone has a solution for it. However, I can only fill the color with a pixel of the touch area, but we have to color on a specific part of the touch with the selected color. Also, be careful that the color must fill the inner border outside or outside the colored border.

if anyone has a sample code please share it.

Thank.