Filter Effects

    import UIKit
    import AudioKit

    class ViewController: UIViewController {

        var filter: AKMoogLadder?
        var delay: AKVariableDelay?
        var delayMixer: AKDryWetMixer?
        var reverb: AKCostelloReverb?
        var reverbMixer: AKDryWetMixer?
        var booster: AKBooster?

        override func viewDidLoad() {
            super.viewDidLoad()

            filter = AKMoogLadder(AKMicrophone())

            delay = AKVariableDelay(filter!)
            delay?.rampTime = 0.5 // Allows for some cool effects
            delayMixer = AKDryWetMixer(filter!, delay!)

            reverb = AKCostelloReverb(delayMixer!)
            reverbMixer = AKDryWetMixer(delayMixer!, reverb!)

            booster = AKBooster(reverbMixer!)

            AudioKit.output = booster
            AudioKit.start()
        }
    }

     override func viewDidLoad() {
        // All the code from before plus the next line:
        setupUI()
    }

    func setupUI() {
        let stackView = UIStackView()
        stackView.axis = .vertical
        stackView.distribution = .fillEqually
        stackView.alignment = .fill
        stackView.translatesAutoresizingMaskIntoConstraints = false

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Cutoff Frequency",
            format: "%0.1f Hz",
            value: self.filter!.cutoffFrequency, minimum: 1, maximum: 2000,
            color: UIColor.orange) { sliderValue in
                self.filter?.cutoffFrequency = sliderValue
        })

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Resonance",
            format: "%0.2f",
            value: self.filter!.resonance, minimum: 0, maximum: 0.99,
            color: UIColor.orange) { sliderValue in
                self.filter?.resonance = sliderValue
        })

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Delay Time",
            format: "%0.2f s",
            value: self.delay!.time, minimum: 0, maximum: 1,
            color: UIColor.green) { sliderValue in
                self.delay?.time = sliderValue
        })

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Delay Feedback",
            format: "%0.2f",
            value: self.delay!.feedback, minimum: 0, maximum: 0.99,
            color: UIColor.green) { sliderValue in
                self.delay?.feedback = sliderValue
        })

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Delay Mix",
            format: "%0.2f",
            value: self.delayMixer!.balance, minimum: 0, maximum: 1,
            color: UIColor.green) { sliderValue in
                self.delayMixer?.balance = sliderValue
        })

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Reverb Feedback",
            format: "%0.2f",
            value: self.reverb!.feedback, minimum: 0, maximum: 0.99,
            color: UIColor.red) { sliderValue in
                self.reverb?.feedback = sliderValue
        })

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Reverb Mix",
            format: "%0.2f",
            value: self.reverbMixer!.balance, minimum: 0, maximum: 1,
            color: UIColor.red) { sliderValue in
                self.reverbMixer?.balance = sliderValue
        })

        stackView.addArrangedSubview(AKPropertySlider(
            property: "Output Volume",
            format: "%0.2f",
            value: self.booster!.gain, minimum: 0, maximum: 2,
            color: UIColor.yellow) { sliderValue in
                self.booster?.gain = sliderValue
        })

        view.addSubview(stackView)

        stackView.widthAnchor.constraint(equalToConstant: view.frame.width).isActive = true
        stackView.heightAnchor.constraint(equalToConstant: view.frame.height).isActive = true

        stackView.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
        stackView.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
    }