Throwable example usage!

Throwable.playground

import Foundation

// MARK: - Throwable
struct Throwable<T: Decodable>: Decodable {
    private let result: Result<T, Error>

    init(from decoder: Decoder) throws {
        do {
            result = .success(try T(from: decoder))
        } catch let error {
            // additionally, logError(error)
            result = .failure(error)
        }
    }

    func get() -> T? {
        try? result.get()
    }
}

// MARK: - Response
struct Response {
    let items: [Widget]
}

extension Response: Decodable {
    enum CodingKeys: CodingKey {
        case items
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        
        let items = try container
            .decode([Throwable<Widget>].self, forKey: .items)
            .compactMap { $0.get() }
        
        guard !items.isEmpty else {
            throw ResponseDecodingError.noWidgets
        }
        
        self.items = items
    }
}

enum ResponseDecodingError: Error {
    case noWidgets
}

// MARK: - Widget
enum Widget {
    case headerWidget(HeaderWidget)
    case cardWidget(CardWidget)
    case buttonWidget(ButtonWidget)
}

extension Widget: Decodable {
    enum `Type`: String, Decodable {
        case headerWidget = "HeaderWidget"
        case cardWidget = "CardWidget"
        case buttonWidget = "ButtonWidget"
    }
    
    enum CodingKeys: String, CodingKey {
        case type
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let type = try container.decode(`Type`.self, forKey: .type)
        
        switch type {
        case .headerWidget:
            self = .headerWidget(try HeaderWidget(from: decoder))
        case .cardWidget:
            self = .cardWidget(try CardWidget(from: decoder))
        case .buttonWidget:
            self = .buttonWidget(try ButtonWidget(from: decoder))
        }
    }
}

// MARK: - Models
struct HeaderWidget: Decodable {
    let title: String
    let subtitle: String
}

struct CardWidget: Decodable {
    let title: String
    let image: URL
    let operation: URL
}

struct ButtonWidget: Decodable {
    let title: String
    let operation: URL
}


let data: Data = """
{
  "items": [
    {
      "type": "HeaderWidget",
      "title": "Hello world",
      "subtitle": "Lorem ipsum"
    },
    {
      "type": "ChartWidget",
      "title": "Your expenses path through the month",
      "data": [3.72, 9.43, 13.72, 16.21, 25.04, 27.95]
    },
    {
      "type": "CardWidget",
      "title": "Your top visits",
      "image": "www.example.com",
      "operation": "app://purchase"
    },
    {
      "type": "ButtonWidget",
      "title": "Subscribe",
      "operation": "app://subscribe"
    }
  ]
}
""".data(using: .utf8)!

let response = try JSONDecoder().decode(Response.self, from: data)