gistfile1.txt

struct Content: Decodable {
    var body: [Body]
}

protocol BodyContent: Decodable {
    func getContent<T: Decodable>() -> T?
}

struct Body: Decodable {
    var type: String
    var content: BodyContent?

    private enum CodingKeys: String, CodingKey {
        case type
        case content
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        self.type = try container.decode(String.self, forKey: .type)

        switch type {
        case "string":
            let contentData = try? container.decode(String.self, forKey: .content)
            self.content = contentData.map { ContentData(content: $0) }
            break
        case "int":
            let contentData = try? container.decode(Int.self, forKey: .content)
            self.content = contentData.map { ContentData(content: $0) }
        default:
            self.content = nil
        }
    }
}

struct ContentData<T: Decodable>: BodyContent {
    let content: T

    func getContent<R>() -> R? where R: Decodable {
        return (content as? R)
    }
}