inheritance failure.swift

import Foundation

struct SoundSample {}


class Effect: Codable {
    // Properties we are intersted in
    var name: String = ""
    var active: Bool = true

    init() {
        self.name = ""
        self.active = true
    }
    
    func doEffect(_ s: SoundSample) -> Void {}

    // stuff for encoding
    private enum CodingKeys: CodingKey {
        case name, active
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.name = try container.decode(String.self, forKey: .name)
        self.active = try container.decode(Bool.self, forKey: .active)
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(name, forKey: .name)
        try container.encode(active, forKey: .active)
    }
}


class ReverbEffect: Effect {
    var delay = 3.2
    var feedback = 40.0

    override init() {
        super.init()
        self.name = "Reverb"
    }

    override func doEffect(_ s: SoundSample) -> Void { /* some custom reverb code here */ }

    // stuff for encoding
    private enum CodingKeys: CodingKey {
        case delay, feedback
    }
    
    required init(from decoder: Decoder) throws {
        try super.init(from: decoder)
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.delay = try container.decode(Double.self, forKey: .delay)
        self.feedback = try container.decode(Double.self, forKey: .feedback)
    }
    
    override func encode(to encoder: Encoder) throws {
        try super.encode(to: encoder)
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(delay, forKey: .delay)
        try container.encode(feedback, forKey: .feedback)
    }
}

class DistortionEffect: Effect {
    var gain = 1.5
    var tone = 6.0

    override init() {
        super.init()
        self.name = "Distortion"
    }
    
    override func doEffect(_ s: SoundSample) -> Void { /* some custom distortion code here */ }

    // stuff for encoding
    private enum CodingKeys: CodingKey {
        case gain, tone
    }
    
    required init(from decoder: Decoder) throws {
        try super.init(from: decoder)
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.gain = try container.decode(Double.self, forKey: .gain)
        self.tone = try container.decode(Double.self, forKey: .tone)
    }
    
    override func encode(to encoder: Encoder) throws {
        try super.encode(to: encoder)
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(gain, forKey: .gain)
        try container.encode(tone, forKey: .tone)
    }
}


let effectsChain = [ReverbEffect(), DistortionEffect()]

// normal operations will be things like this:
let s = SoundSample()
for effect in effectsChain {
    effect.doEffect(s)
}
// Then play sample


// Save our chain as JSON for saving and restoring
do {
    let jsonData = try JSONEncoder().encode(effectsChain)
    let jsonString = String(data: jsonData, encoding: .utf8)

    if let json = jsonString {
        print(json)
    }

    // now restore
    let newChain = try? JSONDecoder().decode([Effect].self, from:jsonData)
    if let new = newChain {
        print("We restored the chain: %@", new)
    }
} catch {
    // blah
}