BindableApplicationBar.BindableApplicationBar.SetButtonsEnabled C# (CSharp) Méthode

        private void SetButtonsEnabled()
        {
            if (this.enabledStates != null && this.enabledStates.Count > 0)
            {
                foreach (var item in enabledStates)
                {
                    var selectedButton = this.Buttons.SingleOrDefault(element => element == item.Key);
                    if (item.Value != null)
                    {
                        selectedButton.SetValue(BindableApplicationBarButton.IsEnabledProperty, item.Value);
                    }
                    else
                    {
                        if (selectedButton.Command != null)
                        {
                            selectedButton.IsEnabled = selectedButton.Command.CanExecute(selectedButton.CommandParameter);
                        }
                        else
                        {
                            selectedButton.IsEnabled = true;
                        }
                    }
                }

                enabledStates = new Dictionary<BindableApplicationBarButton, BindingExpression>();
            }
        }