used by 'A Smart Feature Flagging System for iOS' article on Medium

TweakManager_stack_sample.swift

static let tweakManager: TweakManager = {        
    // mutable configuration (to override tweaks from other configurations)
    let userDefaultsConfiguration = UserDefaultsConfiguration(userDefaults: .standard)

    // remote configurations (optional)
    let optimizelyConfiguration = OptimizelyConfiguration()
    let firebaseConfiguration = FirebaseConfiguration()

    // local JSON configuration (default tweaks)
    let jsonFileURL = Bundle.main.url(forResource: "ExampleConfiguration", withExtension: "json")!
    let localConfiguration = LocalConfiguration(jsonURL: jsonFileURL)

    // priority is defined by the order in the configurations array (from highest to lowest)
    let configurations: [Configuration] = [userDefaultsConfiguration,
                                           optimizelyConfiguration,
                                           firebaseConfiguration,
                                           localConfiguration]
    return TweakManager(configurations: configurations)
}()