Dictionary of String:Any Does Not Conform to Protocol 'Decodable'

Fatal error: DictionaryString, Any does not conform to Decodable because Any does not conform to Decodable

Maybe you are misunderstanding how Codable works. It's based on concrete types. Any is not supported.

In your case you might create a struct like

struct Something: Decodable {
    let success : Bool
    let lastId : Int?
    let hasMore: Bool
    let foundEndpoint: URL
    let error: String?
}

And decode the JSON

func loadLocalJSON() {
    let url = Bundle.main.url(forResource: "localJSON", withExtension: "json")!
    let data  = try! Data(contentsOf: url)
    let colors = try! JSONDecoder().decode(Something.self, from: data)
    print(colors)
}

Any crash will reveal a design error. The sense of using null in a file in the main bundle is another question.

Dictionary of String:Any does not conform to protocol 'Decodable'

You cannot currently decode a [String: Any] with the Swift coding framework. You'll need to drop to a lower-level deserialization strategy and decode “by hand” if you need to decode a [String: Any]. For example, if your input is JSON, you can use Foundation's JSONSerialization or a third-party library like SwiftyJSON.

There has been discussion of this issue on Swift Evolution: “Decode a JSON object of unknown format into a Dictionary with Decodable in Swift 4”. Apple's main Coding/Codable programmer, Itai Ferber, has been involved in the discussion and is interested in providing a solution, but it is unlikely to happen for Swift 5 (which will probably be announced at WWDC 2018 and finalized around September/October 2018).

You could copy the implementation of JSONDecoder (it's open source) into your project and modify it to add the ability to get an unevaluated [String: Any]. Itai discusses the required modifications in the thread I linked above.

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.

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.

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.

Swift Codable: Cannot decode dictionary of type [String: Any] or [String: Decodable]

What you are looking for is nestedContainer. It helps you "skip" a hierarchy level in your JSON. Ie: let's imagine that in your code, it's all in the same level (one struct), but in the JSON, it's not, there is a sub dictionary.

For test purpose, your JSON might look like:

{
    "title": "normal",
    "tracks": {
                   "name": "myName",
                   "total": 3
              }
}

If we want in our model:

struct TestStruct: Codable {
    let title: String
    let name: String
    let total: Int
}

We need to use nestedContainer(keyedBy: forKey:):

extension TestStruct {
    enum TopLevelKeys: String, CodingKey {
        case title
        case tracks
    }
    
    enum NestedLevelCodingKeys: String, CodingKey {
        case name
        case total
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: TopLevelKeys.self)
        self.title = try container.decode(String.self, forKey: .title)
        let subcontainer = try container.nestedContainer(keyedBy: NestedLevelCodingKeys.self, forKey: TopLevelKeys.tracks)
        self.name = try subcontainer.decode(String.self, forKey: .name)
        self.total = try subcontainer.decode(Int.self, forKey: .total) //You can use here a `decodeIfPresent()` if needed, use default values, etc.

    }
}

In your sample, you used decodeIfPresent() for the subdictionary. It's unclear if it was for test purpose, or if the sub dictionary was sometimes not present.
If that's the case and you can have a JSON like this:

{
    "title": "normal"
} 

Then, before calling nestedContainer(keyedBy: forKey:), use if container.contains(TopLevelKeys.tracks) {} and set default values if needed in the else case.

SwiftUI - Type 'Service' does not conform to protocol 'Decodable'

Codable can't have Any , plus businessLocation is a dictionary not an array, so Replace

var businessLocation: Array<Any>

with

var businessLocation:[String:String]

OR

Models

// MARK: - Element
struct Root: Codable {
    let id, name: String
    let items: [Item]
}

// MARK: - Item
struct Service: Codable {
    let id: Int
    let businessName, businessTelephone, businessEmail, businessWebsite: String
    let businessLocation: BusinessLocation
    let travelLimit: Int
    let itemDescription: String
    let categories: [String]

    enum CodingKeys: String, CodingKey {
        case id, businessName, businessTelephone, businessEmail, businessWebsite, businessLocation, travelLimit
        case itemDescription = "description"
        case categories
    }
}

// MARK: - BusinessLocation
struct BusinessLocation: Codable {
    let latitude, longitude: String
}

Decode

do {
    let res = try JSONDecoder().decode([Root].self, from: data)
    print(res)
}
catch {
    print(error)
}

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