This framework makes debugging more efficient in your application.

Sandbox is the name of a structure that improves the efficiency of debugging your application.

Branch the startup Scene at the entry point of your application with using debug flag and the Scene that you want to debug is launched from the beginning.

This framework is introduced in iOSDC 2021.




pod 'SandboxKit'


  1. Install SandboxKit in your application.

  2. Add a new schema from Manage Schemes in Xcode, and specify the environment variable RUNNING_SANDBOX from the Argument item in the Run configuration.

  3. In AppDelegate, check the existence of the environment variable from Prosess, and if it is started with the schema for the Sandbox, specify the rootViewController for Sandbox.

class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        if ProcessInfo.processInfo.environment["RUNNING_MINIAPP"] == "1" {
            window = UIWindow(frame: UIScreen.main.bounds)
            let viewController = ViewController {
                    name: "PokemonDetail",
                    PokemonDetailViewController(id: 133)
                ) {
                    Mock(path: "/pokemons/133", statusCode: 200, method: .get) {
                        JSONData(from: "pokemon")

                /// ....
            window?.rootViewController = UINavigationController(rootViewController: viewController)
            return true

        /// ....
        return true
  1. Inherit SandboxKit.SandboxSceneSelectTableViewController and implement your stub and your initialization.

final class ViewController: SandboxSceneSelectTableViewController {
    override init(@SandboxScenes _ makeScenes: () -> [Scene]) {

    override func initializeScene(_ scene: Scene) {
      /// ....
  1. Select Sandbox schema and launch your application.

See SandboxKitDemo for detailed implementation.


SandboxKit is released under the MIT License.