UserDefaultsStore, Generic UserDefaults Wrapper Using Property Wrapper

UserDefaultsStore.swift

import Foundation

/// UserDefaultsStore, a generic UserDefaults Wrapper store
///
/// How to use:
/// ```
/// enum MyEnum {
///     case myKey
/// }
/// @UserDefaultsStore(
///     type: MyEnum.self,
///     key: .myKey,
///     defaultValue: "MyDefaultValue",
///     store: .myCustomUserDefaults
/// )
/// ```
///
@propertyWrapper
public struct UserDefaultsStore<Keys: RawRepresentable, Value: Codable> where Keys.RawValue == String  {

    // MARK: Private properties

    private let key: Keys
    private let defaultValue: Value
    private let store: UserDefaults

    public init(
        type: Keys.Type,
        key: Keys,
        defaultValue: Value,
        store: UserDefaults = .standard
    ) {
        self.key = key
        self.defaultValue = defaultValue
        self.store = store
    }

    public var wrappedValue: Value {
        get {
            // Read value from UserDefaults
            guard let data = store.object(forKey: key.rawValue) as? Data else {
                // Return defaultValue when no data in UserDefaults
                return defaultValue
            }

            // Convert data to the desire data type
            let value = try? JSONDecoder().decode(Value.self, from: data)
            return value ?? defaultValue
        }
        set {
            // Convert newValue to data
            let data = try? JSONEncoder().encode(newValue)

            // Set value to UserDefaults
            store.set(data, forKey: key.rawValue)
        }
    }
}