What lifecycle methods in MvvmCross are useful for handling push notifications

MvvmCross Lifecycle Methods

MvvmCross provides a set of lifecycle methods for view models that can be used to manage the application's state and handle events such as push notifications. These methods include:

- `ViewCreated`: Called when the view is created. This is a good place to initialize any view-related logic.
- `ViewAppearing`: Called before the view appears. You can use this method to prepare the view model for display.
- `ViewAppeared`: Called after the view has appeared. This is useful for any logic that should run once the view is visible.
- `ViewDisappearing`: Called before the view disappears. Use this to clean up resources or save state.
- `ViewDisappeared`: Called after the view has disappeared. This can be used to finalize any cleanup or state saving.
- `ViewDestroy`: Called when the view is being destroyed. This is a good place to release any resources held by the view model.

However, these lifecycle methods are primarily tied to the view's lifecycle and might not be directly applicable for handling push notifications when the app is not running.

Handling Push Notifications

When the app is not running, and a push notification is received, MvvmCross's lifecycle methods won't be triggered directly. Instead, you can use a different approach:

1. Save Notification Data: When a push notification is received and the app is not running, you can save the notification data in app preferences or a local database. This ensures that the data is preserved until the app is launched.

2. Launch App to Main Activity: Upon receiving a push notification, you can launch the app to its main activity. This will trigger the MvvmCross setup process, allowing you to access the IoC container and other MvvmCross features.

3. Check for Notification Data: In the main activity's `OnCreate` method, check if there is any saved notification data. If data exists, navigate to the appropriate view model using MvvmCross's navigation service.

Custom AppStart for Push Notifications

In MvvmCross 6 and later, you can override the `GetAppStartHint` method to provide hints about how the app should start, such as handling push notifications. This allows you to customize the app's startup behavior based on the presence of notifications.

csharp
public class CustomAppStart : MvxAppStart
{
    public override void RunAppStart(object hint = null)
    {
        if (hint is string notificationHint)
        {
            // Handle the notification hint here
            // Navigate to the appropriate view model
        }
        else
        {
            // Normal app start logic
        }
    }
}

Conclusion

While MvvmCross's lifecycle methods are primarily focused on view-related events, you can leverage them indirectly by saving notification data and navigating to the appropriate view model once the app is launched. Customizing the app start process with hints can also help manage push notifications effectively.