| ### UINavigationItem support | |
| The App Bar begins mirroring the state of your view controller's `navigationItem` in the provided | |
| `navigationBar` once you call `addSubviewsToParent`. | |
| Learn more by reading the Navigation Bar section on | |
| [Observing UINavigationItem instances](../../NavigationBar/#observing-uinavigationitem-instances). | |
| Notably: read the section on "Exceptions" to understand which UINavigationItem are **not** | |
| supported. |