Codable: Does Not Conform to Protocol 'Decodable'

Codable class does not conform to protocol Decodable

Why am I getting a "Type 'Bookmark' does not conform to protocol 'Decodable'" error message

It's either because Publication isn't Decodable (you have not shown what it is, so it's hard to tell) or because of the weak designation on publication.

Either way, it's easy to fix: you just need to implement init(from:) to complete the implementation of Decodable; the compiler is simply telling you that this implementation cannot be synthesized.

Codable class doesn't conform to protocol 'Decodable'

It is not necessary to separate the structs. The error occurs because you have added too many keys in the CodingKeys enum. If you keep only the required ones, then it will work:

struct Model: Codable {
    let aps: Aps
    let link: String?
    let checkAction: String?
   
    enum CodingKeys: String, CodingKey {
           case aps ,link
           case checkAction = "gcm.notificaiton.check_action"
    }
    
    struct Aps: Codable {
        let alert: Alert
        let sound: String?
       
        
        struct Alert: Codable {
            let title: String?
            let body: String?
        }
    }
}

alert, sound etc are not coding keys of Model. They are coding keys of Aps. It is not necessary to specify them in Aps, because they are the same as the property names.

Custom Struct: Type does not conform to protocol 'Decodable'

You will need to make Wish adopt Codable.

But because UIImage and UIColor are not Codable, you’ll have to manually implement them as outlined in Encoding and Decoding Custom Types:

struct Wishlist: Codable {
    var name: String
    var image: UIImage
    var wishes: [Wish]
    var color: UIColor
    var textColor: UIColor
    var index: Int

    enum CodingKeys: String, CodingKey {
        case name, image, wishData, color, textColor, index
    }

    init(name: String, image: UIImage, wishes: [Wish], color: UIColor, textColor: UIColor, index: Int) {
        self.name = name
        self.image = image
        self.wishes = wishes
        self.color = color
        self.textColor = textColor
        self.index = index
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)

        name = try values.decode(String.self, forKey: .name)
        wishes = try values.decode([Wish].self, forKey: .wishData)
        color = try values.decode(Color.self, forKey: .color).uiColor
        textColor = try values.decode(Color.self, forKey: .textColor).uiColor
        index = try values.decode(Int.self, forKey: .index)

        let data = try values.decode(Data.self, forKey: .image)
        guard let image = UIImage(data: data) else {
            throw DecodingError.dataCorruptedError(forKey: .image, in: values, debugDescription: "Invalid image data")
        }
        self.image = image
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)

        try container.encode(name, forKey: .name)
        try container.encode(wishes, forKey: .wishData)
        try container.encode(Color(uiColor: color), forKey: .color)
        try container.encode(Color(uiColor: textColor), forKey: .textColor)
        try container.encode(index, forKey: .index)
        try container.encode(image.pngData(), forKey: .image)
    }

}

struct Wish: Codable {
    public var name: String
    public var checkedStatus: Bool
    public var link: String
    public var price: String
    public var note: String
    public var image: UIImage

    init(name: String, link: String, price: String, note: String, image: UIImage, checkedStatus: Bool) {
        self.name = name
        self.checkedStatus = checkedStatus
        self.link = link
        self.price = price
        self.note = note
        self.image = image
    }

    enum CodingKeys: String, CodingKey {
        case name, checkedStatus, link, price, note, image
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)

        name = try values.decode(String.self, forKey: .name)
        checkedStatus = try values.decode(Bool.self, forKey: .checkedStatus)
        link = try values.decode(String.self, forKey: .link)
        price = try values.decode(String.self, forKey: .price)
        note = try values.decode(String.self, forKey: .note)

        let data = try values.decode(Data.self, forKey: .image)
        guard let image = UIImage(data: data) else {
            throw DecodingError.dataCorruptedError(forKey: .image, in: values, debugDescription: "Invalid image data")
        }
        self.image = image
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)

        try container.encode(name, forKey: .name)
        try container.encode(checkedStatus, forKey: .checkedStatus)
        try container.encode(link, forKey: .link)
        try container.encode(price, forKey: .price)
        try container.encode(note, forKey: .note)
        try container.encode(image.pngData(), forKey: .image)
    }
}

Where I’d use this as a convenient way to encode UIColor objects:

struct Color: Codable {
    let red: CGFloat
    let green: CGFloat
    let blue: CGFloat
    let alpha: CGFloat

    init(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {
        self.red = red
        self.green = green
        self.blue = blue
        self.alpha = alpha
    }

    init(uiColor: UIColor) {
        var red: CGFloat = 0
        var green: CGFloat = 0
        var blue: CGFloat = 0
        var alpha: CGFloat = 0

        uiColor.getRed(&red, green: &green, blue: &blue, alpha: &alpha)

        self.red = red
        self.green = green
        self.blue = blue
        self.alpha = alpha
    }

    var uiColor: UIColor { UIColor(red: red, green: green, blue: blue, alpha: alpha) }
}

Note, I did a couple of unrelated changes:

• I made both of these struct. I wouldn’t introduce reference types (much less NSObject subclasses) unless necessary.

• I simplified some of the property names. E.g. in Wish, we wouldn’t generally use wish prefix in property names. I also wouldn’t use “data” in a property name unless it was, in fact, a Data.

• I updated init methods to use standard naming conventions.

My structure does not conform to protocol 'Decodable' / 'Encodable' if I use protocol type in my structure in swift

JSONDecoder needs to know the concrete type of thing that you want to decode the JSON into. After all, everything must have a concrete type at runtime, that you can get with type(of:). You can't tell it to just "decode a protocol". The encoder is a bit different though - it doesn't actually need to know the concrete type, and there is a way to get around it.

It seems like the type of UIConfig depends on objectid, so we can check objectid and decide what type of UIConfig to decode:

enum CodingKeys: CodingKey {
    case id, objectid, config
}

init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    id = try container.decode(String.self, forKey: .id)
    objectid = try container.decode(String.self, forKey: .objectid)
    if objectid == "bd_label" {
        config = try container.decode(LabelConfig.self, forKey: .config)
    } else if objectid == "bd_button" {
        config = try container.decode(ButtonConfig.self, forKey: .config)
    } 
    // other cases...
    else {
        throw DecodingError.dataCorruptedError(forKey: .config, in: container, debugDescription: "no suitable config type found for objectid \(objectid)!")
    } 
}

For the Encodable part, you can make a "type eraser"-like thingy:

struct AnyEncodable: Encodable {
    let encodeFunction: (Encoder) throws -> Void
    
    init(_ encodable: Encodable) {
        encodeFunction = encodable.encode(to:)
    }
    
    func encode(to encoder: Encoder) throws {
        try encodeFunction(encoder)
    }
}

and do:

func encode(to encoder: Encoder) throws {
    var container = encoder.container(keyedBy: CodingKeys.self)
    try container.encode(id, forKey: .id)
    try container.encode(objectid, forKey: .objectid)
    try container.encode(AnyEncodable(config), forKey: .config)
}

By using AnyEncodable, we are basically wrapping the protocol in a concrete type, but don't worry - this won't actually create an extra pair of curly brackets in the JSON.

Type 'Model' does not conform to protocol 'Decodable'/Encodable

A @Published property with type, let's say, String, are of type Published<String>. And apparently, that type is not Codable.

You can solve this by writing custom encode and decode functions. That's not difficult; it's only some extra lines of code. Please see the documentation on Codable for some examples.

Here is an example for your case:

class TimeModel: Codable, Identifiable, ObservableObject {
    @Published var id: UUID = UUID()
    @Published var nome : String
    @Published var time : String
    
    func aggiornaUI() {
        DispatchQueue.main.async {
            self.objectWillChange.send()
        }
    }
    
    init(nome: String, time: String) {
        self.nome = nome
        self.time = time
    }
    
    enum CodingKeys: String, CodingKey {
        case id
        case nome
        case time
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(id, forKey: .id)
        try container.encode(nome, forKey: .nome)
        try container.encode(time, forKey: .time)
    }
    
    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        id = try container.decode(UUID.self, forKey: .id)
        nome = try container.decode(String.self, forKey: .nome)
        time = try container.decode(String.self, forKey: .time)
    }
}

This should work, but I can't really test it because I don't know the rest of your code.

Type does not conform to protocol 'Decodable'/'Encodable'

Every property in a Codable type must also be Codable as well.

The simplest way to make a type codable is to declare its properties
using types that are already Codable.

1. Built-in Codable types — String, Int, Double, Data, URL Array,

2. Dictionary, Optional are Codable if they contain Codable types

Hence, the AdditionalCharge must also be Codable for FundingRequest to be Codable.

class AdditionalCharge: Codable {
    var ItemDescription = ""
    var ItemValue:String = ""
}

Type '' does not conform to protocol 'Decodable'/'Encodable'

Instead of NSNumber use native Swift types, like Double, and align other code to that

struct Spty: Identifiable, Codable{
   @DocumentID var id: String? = UUID().uuidString
   var spty: String
   var r: Double
   var g: Double
   var b: Double
}

Type 'PlayerData' does not conform to protocol 'Decodable' and 'Encodable'

Player should conform also

class Player : Codable {

Type 'Response' does not conform to protocol 'Decodable' \ 'Encodable'

The issue is caused by the fact that you declared both properties of Response as implicitly unwrapped optionals (IOU). The compiler cannot autogenerate the required methods of Codable for IOU properties.

However, there's no need to make those IOU anyways. If they are required properties that are always present in the response, make them non-optional. If they might be missing, make them Optional (use ? instead of !).

Also, Swift is not Objective-C. There's no need to make your types inherit from NSObject. And you should also use structs instead of classes unless you explicitly need reference type behaviour. You should also make all properties immutable unless you explicitly need to be able to mutate them.

struct ErrorObj: Codable {
    let numError: Int
    let description: String
}

struct Response<T: Codable>: Codable {
    let error: ErrorObj
    let result: T

    func getResponse(errorObj: (ErrorObj) -> Void, successObj: (T) -> Void) {
        if error.numError != 0 {
            errorObj(error)
        } else{
            successObj(result)
        }
    }

}

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