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Other Projects/Currency-SwiftUI/Currency-SwiftUI/UserData.swift

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+//
+//  UserData.swift
+//  Currency-SwiftUI
+//
+//  Created by Alex Liu on 2019-06-20.
+//  Copyright © 2018 Alex Liu <alexliubo@gmail.com> All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+
+import Combine
+import SwiftUI
+import Foundation
+
+private let defaultCurrencies: [Currency] = [
+    Currency(name: "US dollar", rate: 1.0, symbol: "US", code: "USD"),
+    Currency(name: "Canadian dollar", rate: 1.0, symbol: "CA", code: "CAD")
+]
+
+@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)
+        }
+    }
+}
+
+final class UserData: BindableObject {
+    let didChange = PassthroughSubject<UserData, Never>()
+    
+    @UserDefaultValue(key: "allCurrencies", defaultValue: defaultCurrencies)
+    var allCurrencies: [Currency] {
+        didSet {
+            didChange.send(self)
+        }
+    }
+    
+    @UserDefaultValue(key: "baseCurrency", defaultValue: defaultCurrencies[0])
+    var baseCurrency: Currency {
+        didSet {
+            didChange.send(self)
+        }
+    }
+    
+    @UserDefaultValue(key: "userCurrency", defaultValue: defaultCurrencies)
+    var userCurrency: [Currency] {
+        didSet {
+            didChange.send(self)
+        }
+    }
+}
+