Fun example for abstracting delegate into a Type with a closure

AVSpeechSynthGlue.swift

import SwiftUI
import AVFoundation

class AVSpeechSynthGlue: NSObject, AVSpeechSynthesizerDelegate {
    enum State {
        case didStart(AVSpeechUtterance)
        case willSpeakRangeOfSpeechString(NSRange)
        case willSpeak(AVSpeechSynthesisMarker)
        case didPause(AVSpeechUtterance)
        case didContinue(AVSpeechUtterance)
        case didFinish(AVSpeechUtterance)
        case didCancel(AVSpeechUtterance)
    }
    let synth = AVSpeechSynthesizer()

    let stateHandler: ((State) -> ())?

    init(_ stateHandler: @escaping (State) -> ()) {
        self.stateHandler = stateHandler
        super.init()
        synth.delegate = self
    }

    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didStart: AVSpeechUtterance) {
        stateHandler?(.didStart(didStart))
    }
    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, willSpeakRangeOfSpeechString: NSRange, utterance: AVSpeechUtterance) {
        stateHandler?(.willSpeakRangeOfSpeechString(willSpeakRangeOfSpeechString))
    }
    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, willSpeak: AVSpeechSynthesisMarker, utterance: AVSpeechUtterance) {
        stateHandler?(.willSpeak(willSpeak))
    }
    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didPause: AVSpeechUtterance) {
        stateHandler?(.didPause(didPause))
    }
    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didContinue: AVSpeechUtterance) {
        stateHandler?(.didContinue(didContinue))
    }
    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didFinish: AVSpeechUtterance) {
        stateHandler?(.didFinish(didFinish))
    }
    func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didCancel: AVSpeechUtterance) {
        stateHandler?(.didCancel(didCancel))
    }
}

struct PodBay: View {
    let synthGlue: AVSpeechSynthGlue = .init {
        switch $0 {
        case .didStart(let aVSpeechUtterance):
            print("Started")
        case .willSpeakRangeOfSpeechString(let nSRange):
            print("spoke range")
        case .willSpeak(let aVSpeechSynthesisMarker):
            print("Will Speek")
        case .didPause(let aVSpeechUtterance):
            print("did Pause")
        case .didContinue(let aVSpeechUtterance):
            print("did continue")
        case .didFinish(let aVSpeechUtterance):
            print("did finish")
        case .didCancel(let aVSpeechUtterance):
            print("did cancel")
        }
    }

    var synth: AVSpeechSynthesizer { synthGlue.synth }

    var body: some View {
        VStack(spacing: 16) {
            Button("Open the Pod Bay doors") {
                synth.speak(.init(string: "I'm sorry Dave, I'm afraid I can't do that"))
            }
            Button("Pause") {
                synth.pauseSpeaking(at: .immediate)
            }
            Button("Continue") {
                synth.continueSpeaking()
            }
            Button("Cancel") {
                synth.stopSpeaking(at: .immediate)
            }
        }.padding()
    }
}