How do I get the color of a pixel in a UIImage with Swift?

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A bit of searching leads me here since I was facing the similar problem.
You code works fine. The problem might be raised from your image.

Code: 

  //On the top of your swift 
  extension UIImage {
      func getPixelColor(pos: CGPoint) -> UIColor {

          let pixelData = CGDataProviderCopyData(CGImageGetDataProvider(self.CGImage))
          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)
      }  
  }

What happens is this method will pick the pixel colour from the image’s CGImage. So make sure you are picking from the right image. e.g. If you UIImage is 200×200, but the original image file from Imgaes.xcassets or wherever it came from, is 400×400, and you are picking point (100,100), you are actually picking the point on the upper left section of the image, instead of middle.

Two Solutions:
1, Use image from Imgaes.xcassets, and only put one @1x image in 1x field. Leave the @2x, @3x blank. Make sure you know the image size, and pick a point that is within the range. 

//Make sure only 1x image is set
let image : UIImage = UIImage(named:"imageName") 
//Make sure point is within the image
let color : UIColor = image.getPixelColor(CGPointMake(xValue, yValue))

2, Scale you CGPoint up/down the proportion to match the UIImage. e.g. let point = CGPoint(100,100) in the example above, 

let xCoordinate : Float = Float(point.x) * (400.0/200.0)
let yCoordinate : Float = Float(point.y) * (400.0/200.0) 
let newCoordinate : CGPoint = CGPointMake(CGFloat(xCoordinate), CGFloat(yCoordinate))
let image : UIImage = largeImage
let color : UIColor = image.getPixelColor(CGPointMake(xValue, yValue))

I’ve only tested the first method, and I am using it to get a colour off a colour palette. Both should work.
Happy coding 🙂

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