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

If you are calling the answered question more than once, than you should not use the function on every pixel, because you are recreating the same set of data. If you want all of the colors in an image, do something more like this:

func findColors(_ image: UIImage) -> [UIColor] {
    let pixelsWide = Int(image.size.width)
    let pixelsHigh = Int(image.size.height)

    guard let pixelData = image.cgImage?.dataProvider?.data else { return [] }
    let data: UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData)

    var imageColors: [UIColor] = []
    for x in 0..<pixelsWide {
        for y in 0..<pixelsHigh {
            let point = CGPoint(x: x, y: y)
            let pixelInfo: Int = ((pixelsWide * Int(point.y)) + Int(point.x)) * 4
            let color = UIColor(red: CGFloat(data[pixelInfo]) / 255.0,
                                green: CGFloat(data[pixelInfo + 1]) / 255.0,
                                blue: CGFloat(data[pixelInfo + 2]) / 255.0,
                                alpha: CGFloat(data[pixelInfo + 3]) / 255.0)
            imageColors.append(color)
        }
    }
    return imageColors
}

Here is an Example Project

As a side note, this function is significantly faster than the accepted answer, but it gives a less defined result.. I just put the UIImageView in the sourceView parameter.

func getPixelColorAtPoint(point: CGPoint, sourceView: UIView) -> UIColor {
    let pixel = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: 4)
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
    let context = CGContext(data: pixel, width: 1, height: 1, bitsPerComponent: 8, bytesPerRow: 4, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)

    context!.translateBy(x: -point.x, y: -point.y)

    sourceView.layer.render(in: context!)
    let color: UIColor = UIColor(red: CGFloat(pixel[0])/255.0,
                                 green: CGFloat(pixel[1])/255.0,
                                 blue: CGFloat(pixel[2])/255.0,
                                 alpha: CGFloat(pixel[3])/255.0)
    pixel.deallocate(capacity: 4)
    return color
}

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 200x200, but the original image file from Imgaes.xcassets or wherever it came from, is 400x400, 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 :)

SWIFT 3, XCODE 8 Tested and working

extension UIImage {
    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)
    }

}