Interface ILifecycleAware

Namespace

Crystal.Avalonia

Assembly

Crystal.Avalonia.dll

Defines lifecycle hooks for ViewModel initialization and cleanup when used with ViewModelLocator or ViewLocator.

public interface ILifecycleAware

Examples

public class MyViewModel : ObservableObject, ILifecycleAware
{
    public async Task OnLoadedAsync(bool isFirstLoad)
    {
        if (!isFirstLoad) return;
        await LoadDataAsync();
    }

    public Task OnUnloaded() => Task.CompletedTask;
}

Remarks

Both ViewModelLocator and ViewLocator subscribe to the View's Loaded and Unloaded events when the DataContext implements this interface. OnLoadedAsync(bool) is invoked on every Loaded. The isFirstLoad argument is true only the first time that ViewModel instance is loaded. Transient ViewModels therefore always see true; a singleton sees false on later visits. OnUnloaded() is invoked on every Unload. Exceptions are caught and written to Trace.

Methods

OnLoadedAsync(bool)

Called when the View is loaded and ready for interaction.

Task OnLoadedAsync(bool isFirstLoad)

Parameters

isFirstLoad bool

true the first time this ViewModel instance is loaded; false on subsequent loads of the same instance (for example a singleton after navigation).

Returns

Task

OnUnloaded()

Called when the View is unloaded and no longer part of the visual tree. Invoked on every unload.

Task OnUnloaded()

Returns

Task