Property Wrapper in Swift - Article

property-wrapper-2.swift

@propertyWrapper
struct Store {

    // Key for UserDefaults
    var key: String
    
    // This is the special variable required in Property Wrapper.
    var wrappedValue: Bool {
        set { UserDefaults.standard.set(newValue, forKey: key) }
        get { UserDefaults.standard.value(forKey: key) as? Bool ?? false }
    }
    
    init(key: String) {
        self.key = key
    }
}

// Now we can simplify our AppSettings struct as
struct AppSettings {
    @Store(key: "is_dark_mode_enabled") static var isDarkModeEnabled: Bool
}

// value `true` is automatically stored in user defaults with key `is_dark_mode_enabled`
AppSettings.isDarkModeEnabled = true