private void attachMeasuredRootViewToInstance( ReactRootView rootView, CatalystInstance catalystInstance) { UiThreadUtil.assertOnUiThread(); // Reset view content as it's going to be populated by the application content from JS rootView.removeAllViews(); rootView.setId(View.NO_ID); UIManagerModule uiManagerModule = catalystInstance.getNativeModule(UIManagerModule.class); int rootTag = uiManagerModule.addMeasuredRootView(rootView); @Nullable Bundle launchOptions = rootView.getLaunchOptions(); WritableMap initialProps = launchOptions != null ? Arguments.fromBundle(launchOptions) : Arguments.createMap(); String jsAppModuleName = rootView.getJSModuleName(); WritableNativeMap appParams = new WritableNativeMap(); appParams.putDouble("rootTag", rootTag); appParams.putMap("initialProps", initialProps); catalystInstance.getJSModule(AppRegistry.class).runApplication(jsAppModuleName, appParams); }