title: JSONDecoder with no output in Swift Playground
body: <p>I am new to <code>Swift</code> <code>JSON</code>, so I am practicing in <code>Swift Playgrounds</code>. I'm pretty sure that this would be considered decoding a nested <code>JSON</code> key. But like I said, I'm new and I am not familiar with all of the technical terms.</p>
  
  <p>Anyway, I thought that this code was right, but for some reason it won't print. And it's not showing me any error, which is making it harder to fix. But, I must be doing something wrong. </p>
  
  <pre><code>import UIKit
  
  let jsonData :Data = """
  {
  "id": 1,
  "name": "John Smith",
  "username": "Johnny",
  "email": "Johnny@yahoo.com",
  "address": {
      "street": "Some Street",
      "suite": "100",
      "city": "SomeCity",
      "zipcode": "12345",
      }
  }
  
  """.data(using: .utf8)!
  
  struct User :Decodable {
  
      let id :Int
      let name :String
      let userName :String
      let email :String
  
      let street :String
      let suite :String
      let city :String
      let zipCode :String
  
      private enum UserKeys :String, CodingKey {
          case id
          case name
          case userName
          case email
          case address
      }
  
      private enum AddressKeys :String, CodingKey {
  
          case street
          case suite
          case city
          case zipCode
  
      }
  
      init(from decoder :Decoder) throws {
  
          let userContainer = try decoder.container(keyedBy: UserKeys.self)
  
          self.id = try userContainer.decode(Int.self, forKey: .id)
          self.name = try userContainer.decode(String.self, forKey: .name)
          self.userName = try userContainer.decode(String.self, forKey: .userName)
          self.email = try userContainer.decode(String.self, forKey: .email)
  
          let addressContainer = try userContainer.nestedContainer(keyedBy: AddressKeys.self, forKey: .address)
  
          self.street = try addressContainer.decode(String.self, forKey: .street)
          self.suite = try addressContainer.decode(String.self, forKey: .suite)
          self.city = try addressContainer.decode(String.self, forKey: .city)
          self.zipCode = try addressContainer.decode(String.self, forKey: .zipCode)
  
      }
  
  }
  
  if let user = try? JSONDecoder().decode(User.self, from: jsonData) {
      print(user.name)
      print(user.city)
  }
  </code></pre>