# Lifecycle and App Upgrades

## Closing a Screen

Closing the screen does not stop region downloads automatically. To pause or cancel a download, call the corresponding region-control method explicitly.

-   Cancel _progressSubscription_ to stop screen-level observation.
    
-   Call _endDownloadPage_ to release ownership of the offline map screen.
    
-   Do not call _shutdownOffline_ when closing a screen, ending one navigation session, or moving the app to the background.
    

## Shutting Down the Offline Subsystem

Infrequent lifecycle operation:

```swift
// Call only when ending the entire offline subsystem lifecycle.

await NBNavigation.shutdownOffline()

//Reinitialize before using an offline API again.

try await NBNavigation.initializeOffline()
```

_shutdownOffline_ stops shared progress observation, releases download-screen ownership, cancels native activity, and releases engine resources. It does not delete offline region data from disk. Normal app lifecycles usually do not need to call it.

## App Upgrades and Data Retention

| Scenario | Offline-data result | Requirement |
| --- | --- | --- |
| In-place update with the same Bundle ID | The sandbox is normally preserved and the default offline directory remains available | Keep the Bundle ID unchanged and do not delete data programmatically |
| Uninstall and reinstall | The system deletes the app sandbox and offline data is lost | The app must clearly prompt the user to download the data again |
| Change the Bundle ID or signing container | The app uses a new sandbox container | Treat as a new installation |
| Custom dataRoot location changes | Existing data remains in the previous directory and the new engine cannot read it | Derive the same subdirectory from Application Support on every launch |
| Call deleteRegionAllData | Routing and map data for the region is deleted | Trigger only in response to an explicit user action |

### Upgrade requirement

Leave `dataRoot` unset whenever possible so SDK 4.1.4 resolves the default directory from “Application Support” on every launch. If a custom location is required, resolve “Application Support” again on every launch and append a fixed subdirectory. Do not persist in an absolute sandbox path. The SDK performs supported database migrations during initialization. The app must not modify database files or `schema_version`.