Added sketch file with table of content

Author: Bob Lee

course/swift4/codable-json.md

@@ -1,9 +1,94 @@
 # Codable and JSON Serialization
 ## Introduction
 ## Problem
-
+Map JSON to Object in one line of code
 
 ## Conclusion
 
+```swift
+let republicOfKorea = JSON(dictionary: [
+  "capital": "Seoul",
+  "name": "Republic of Korea",
+  "population": 50000000
+  ])
+
+let koreaCaital: String? = republicOfKorea["capital"]
+let koreaName: String? = republicOfKorea["name"]
+let koreaPopulation: Int? = republicOfKorea["population"]
+```
+
+### Import Foundation
+```swift
+import Foundation
+```
+
+### Design Model
+
+```
+struct User: Codable {
+  var name : String
+  var loginMethods : [LoginMethods]
+  var numberOfFriends : Int
+}
+
+enum LoginMethods: String, Codable {
+  case facebook, instagram, linkedin, twitter
+}
+```
+
+### Create Object
+```swift
+let bob = User(name: "Up", loginMethods: [.facebook, .instagram], numberOfFriends : 4)
+```
+
+### Encode (Object to JSON)
+
+```swift
+//: Create Encoder
+let jsonEncoder = JSONEncoder()
+```
+
+#### Customize Encoder
+```swift
+jsonEncoder.outputFormatting = .prettyPrinted
+jsonEncoder.dataEncodingStrategy = .base64Encode
+```
+
+#### Execution
+```swift
+//: Encode
+var data: Data?
+
+do {
+  let jsonData = try jsonEncoder.encode(bob)
+  data = jsonData
+  let jsonString = String(data: jsonData, encoding: .utf8)
+  print("JSON String : " + jsonString!)
+}
+catch(let error) {
+  print(error)
+}
+```
+
+### Decode (JSON to Object)
+
+#### Create Decoder
+```swift
+let jsonDecoder = JSONDecoder()
+```
+
+#### Execution
+```swift
+do {
+  let bob = try jsonDecoder.decode(User.self, from: data!)
+  // let bob = try jsonDecoder.decode(AnotherUser.self, from: data!)
+  print("Name : \(bob.name)")
+  print("Number of friends: \(bob.numberOfFriends)")
+} catch(let error) {
+  print(error)
+}
+```
+
 ### Source Code
+[9004_json_serialization_codable]()
 ### Resources

source-code/9000_swift4/.DS_Store

@@ -1,15 +1,13 @@
 /*:
  ## Learn Swift with Bob
  ### What's New in Swift 4
- ### Codable and JSON Serialization
+ ### 9004_Codable and JSON Serialization
 
  **Problem:** Map JSON to Object in one line of code
 
  ---
 
  */
-//: Import Foundation
-import Foundation
 
 //: Your Past
 /*
@@ -25,6 +23,10 @@ let koreaPopulation: Int? = republicOfKorea["population"]
  */
 
 
+//: Import Foundation
+import Foundation
+
+
 //: Design Model
 struct User: Codable {
   var name : String

source-code/9000_swift4/9004_codable_json.playground/Pages/8001_nested_generics_recursive_enum.xcplaygroundpage/Contents.swift

@@ -50,7 +50,6 @@
 - 6002_Filter
 - 6003_Map
 - 6004_Reduce
-- 6005_Flatmap
 
 ### Chapter 7:  Generic Protocol
 - 7001_Intro Protocol Associated Type