a.swift

a.swift

// WARNING: This does not compile
extension UIImage: Codable {
  // 'required' initializer must be declared directly in class 'UIImage' (not in an extension)
  public required init(from decoder: Decoder) throws {
    let container = try decoder.singleValueContainer()
    let data = try container.decode(Data.self)
    guard let image = UIImage(data: data) else {
      throw MyError.decodingFailed
    }

    // A non-failable initializer cannot delegate to failable initializer 'init(data:)' written with 'init?'
    self.init(data: data)
  }

  public func encode(to encoder: Encoder) throws {
    var container = encoder.singleValueContainer()
    guard let data = UIImagePNGRepresentation(self) else {
      return
    }

    try container.encode(data)
  }
}