Adding multiple effects to a photo - ios

Question

How can I add several effects to a picture? I have the following code that adds an effect to a photo:
func applyEffects(name: String, n: Float) {
filter.setValue(self.cImage, forKeyPath: kCIInputImageKey)
filter.setValue(n, forKeyPath: name)
let result = filter.value(forKey: kCIOutputImageKey) as! CIImage
let cgImage = CIContext.init(options: nil).createCGImage(result, from: result.extent)
self.customImage = UIImage.init(cgImage: cgImage!)
}
func brightness(n: Float) {
self.applyEffects(name: kCIInputBrightnessKey, n: n)
}
func contrast(n: Float) {
self.applyEffects(name: kCIInputContrastKey, n: n)
}
func saturation(n: Float) {
self.applyEffects(name: kCIInputSaturationKey, n: n)
}
But when I want to apply the second effect, the first one disappears. How can I overlay two or more effects on each other?

Answer 1

I'm assuming you are using CIColorControls as your filter.
You need to pass all three values into your call:
// The documentation doesn't give a default value for contrast, but for the others, I'm setting the defaults
var brightness:Float = 1
var contrast:Float = 1
var saturation:Float = 1
func applyEffects() {
filter.setValue(self.cImage, forKeyPath: kCIInputImageKey)
filter.setValue(brightness, forKeyPath: kCIInputBrightnessKey)
filter.setValue(contrast, forKeyPath: kCIInputContrastKey)
filter.setValue(saturation, forKeyPath: kCIInputSaturationKey)
let result = filter.value(forKey: kCIOutputImageKey) as! CIImage
let cgImage = CIContext.init(options: nil).createCGImage(result, from: result.extent)
self.customImage = UIImage.init(cgImage: cgImage!)
}
func brightness(n: Float) {
brightness = n
applyEffects()
}
func contrast(n: Float) {
contrast = n
applyEffects()
}
func saturation(n: Float) {
saturation = n
applyEffects()
}
A suggestion:
If you are trying to use "real-time" updating via UISliders, use a GLKView and send in the CIImage directly. It uses the GPU, and performance on a device is greatly increased. You can always create a UIImage for saving, messaging, etc.