Swift - How to set initial value for NSUserDefaults

Swift 3 syntax example

Register a boolean default value:

UserDefaults.standard.register(defaults: ["SoundActive" : true])

And to get the value:

UserDefaults.standard.bool(forKey: "SoundActive")

Sidenote: Although the above code will return true, note that the value isn't actually written to disk until you set it:

UserDefaults.standard.set(true, forKey: "SoundActive")

Add this to your didFinishLaunchingWithOptions method from the AppDelegate. As some others pointed out try not to abuse by putting everything in this method.

 func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {    /// Here you can give default values to your UserDefault keys    UserDefaults.standard.register(defaults: [        "SoundActive": true,        "someOtherKey": "Some Message"        ])}

Swift 4

I prefer to implement a function similar to UserDefaults.string(forKey: ) which returns nil if the value is not set. Combined with the ?? operator, you don't need to have any default values written to disk unless you explicitly set them later.

extension UserDefaults {    public func optionalInt(forKey defaultName: String) -> Int? {        let defaults = self        if let value = defaults.value(forKey: defaultName) {            return value as? Int        }        return nil    }    public func optionalBool(forKey defaultName: String) -> Bool? {        let defaults = self        if let value = defaults.value(forKey: defaultName) {            return value as? Bool        }        return nil    }}

Then you can retrieve your default values as follows

let defaults = UserDefaults.standardlet userName = defaults.string(forKey: "Username") ?? "Happy"let userAge = defaults.optionalInt(forKey: "Age") ?? 21let isSmart = defaults.optionalBool(forKey: "Smart") ?? true