public static Task <TResult> InvokeAsync <TViewModel, TResult>(this ViewModel viewModel, Action <TViewModel, Page> activateAction, bool animation = true)
where TViewModel : FunctionViewModel <TResult>
{
var helper = new InvokeHelper <TViewModel, TResult>();
viewModel.Navigation.PushAsync <TViewModel>(
(vm, v) =>
{
vm.Result = default(TResult);
if (activateAction != null)
{
activateAction(vm, v);
}
helper.Attach(vm, v);
});
return(helper.TaskCompletionSource.Task);
}