Add examples project

Examples/Example To-Do App/SwiftUITodo/UserDefaultsValue.swift

@@ -0,0 +1,28 @@
+//
+//  UserDefaultsValue.swift
+//  SwiftUITodo
+//
+//  Created by kemchenj on 2019/6/5.
+//  Copyright © 2019 Suyeol Jeon. All rights reserved.
+//
+
+import Foundation
+
+@propertyDelegate
+struct UserDefaultValue<Value: Codable> {
+
+    let key: String
+    let defaultValue: Value
+
+    var value: Value {
+        get {
+            let data = UserDefaults.standard.data(forKey: key)
+            let value = data.flatMap { try? JSONDecoder().decode(Value.self, from: $0) }
+            return value ?? defaultValue
+        }
+        set {
+            let data = try? JSONEncoder().encode(newValue)
+            UserDefaults.standard.set(data, forKey: key)
+        }
+    }
+}