Swift Cannot remove CIFIlter from UIImage

Question

been working on swift for a bit now and having trouble tackling this Core Image Framework. I was able to successfully create a CIFilter over an image however I\'m not sure

Answer 1

You can do this by keeping previous value in a variable or if you have multiple filters keep that values in a dictionary. When you are applying a new filter or changing value of existing filter, just replace that value with new value and apply all values on original CIImage

For example,

    var allFilters = [String: [String: Any]]()
    var currentImage: CIImage!
    let kCIColorControls = "CIColorControls"

    override func viewDidLoad() {
        super.viewDidLoad()
        currentImage = CIImage(image: self.originalImage!)
    }

    func applyAvailableFilters() {
            if self.allFilters.count > 0 {            
                DispatchQueue.global(qos: .background).async {
                    var outputImage: CIImage!

                    self.blurFilter = CIFilter.init(name: "CIGaussianBlur")
                    self.brightnessFilter = CIFilter.init(name: "CIColorControls")
                    self.cropFilter = CIFilter.init(name: "CICrop")

                    if let blurProperty = self.allFilters[self.kCIGaussianBlur]?.first {
                        self.blurFilter.setValue(blurProperty.value, forKey: blurProperty.key)
                                                self.blurFilter.setValue(self.currentImage, forKey: kCIInputImageKey)
                        outputImage = self.blurFilter.outputImage
                    }

                    if let brightnessProperty = self.allFilters[self.kCIColorControls]?.first {
                        self.brightnessFilter.setValue(brightnessProperty.value, forKey: brightnessProperty.key)
                        if let outputImage = self.blurFilter.outputImage {
                            self.brightnessFilter.setValue(outputImage, forKey: kCIInputImageKey)
                        } else {
                            self.brightnessFilter.setValue(self.currentImage, forKey: kCIInputImageKey)
                        }
                        outputImage = self.brightnessFilter.outputImage
                    }

                    if let cropProperty = self.allFilters[self.kCICrop]?.first {
                        self.cropFilter.setValue(cropProperty.value, forKey: cropProperty.key)
                        if let outputImage = self.brightnessFilter.outputImage {
                            self.cropFilter.setValue(outputImage, forKey: kCIInputImageKey)
                        } else if let outputImage = self.blurFilter.outputImage {
                            self.cropFilter.setValue(outputImage, forKey: kCIInputImageKey)
                        } else {
                            self.cropFilter.setValue(self.currentImage, forKey: kCIInputImageKey)
                        }
                        outputImage = self.cropFilter.outputImage
                    }

                    if let image = outputImage {
                        let openGLContext = EAGLContext(api: .openGLES2)
                        let context = CIContext(eaglContext: openGLContext!)
                        if let cgimg = context.createCGImage(image, from: image.extent) {
                            let processedImage = UIImage(cgImage: cgimg)
                            DispatchQueue.main.async {
                                self.imageView.image = processedImage
                            }
                        }
                    } else {
                        DispatchQueue.main.async {
                            self.imageView.image = self.selectedImage
                        }
                    }
                }
            } else {
                DispatchQueue.main.async {
                    self.imageView.image = self.selectedImage
                }
            }
        }

Then apply your filter like this (Blur filter)

@IBAction func sliderValueChanged(_ sender: UISlider) {
      if sender.value == 0 {
            _ = allFilters.removeValue(forKey: kCIGaussianBlur)
        } else {
            allFilters[kCIGaussianBlur] = [kCIInputRadiusKey: sender.value]
        }
        if allFilters[kCICrop]?.first == nil {
            allFilters[kCICrop] = ["inputRectangle": CIVector(cgRect: self.currentImage.extent)]
        }
        applyAvailableFilters()
}