Demonstrates how api data can be fetched from a webservice when a viewmodel is initially loaded.

ViewModelAsyncLoad.cs

public class ExampleViewModel : INotifyPropertyChanged
{
    private readonly IDataObjectService _dataObjectService;

    ObservableCollection<DataObject> _bindedList;
    ObservableCollection<DataObject> BindedList
    {
        get { return _bindedList; }
    }

    public ExampleViewModel()
    {
        _dataObjectService = new DataObjectService();

        Task.Run(() => GetViewModelData);
    }

    private Task GetViewModelData()
    {
        var data = await _dataObjectService.GetData();

        _bindedList = new ObservableCollection(data);

        OnPropertyChanged(nameof(BindedList));
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}