gistfile1.txt

import UIKit
import CoreImage

class CustomFilter : CIFilter {
  var privateInputImage: CIImage?
  var inputImage: CIImage? {
  set {
    privateInputImage = newValue
  }
  get {
    return privateInputImage
  }
  }
  func outputImage() -> CIImage {
    let colorControls = CIFilter(name: "CIColorControls")
    colorControls.setValue(0.0, forKey: "inputSaturation")
    colorControls.setValue(privateInputImage, forKey: "inputImage")

    return colorControls.outputImage
  }
}