Question

i have a query like this, and it throws me an error, which says imgSortUp does not exist in the current context. Is this a bug? Any ideas? It was just working fine before I put the declaration of images inside the if statement. Any help would be appreciated.

ContentPresenter cp = (sender as Grid).GetVisualDescendants().OfType<ContentPresenter>().SingleOrDefault();
        if (cp.Content.ToString() == "Work Order #" || cp.Content.ToString() == "Status")
        {
            Image imgSortUp = (sender as Grid).GetVisualDescendants().OfType<Image>().Where(i => i.Name == "SortIconUp").SingleOrDefault();
            Image imgSortDown = (sender as Grid).GetVisualDescendants().OfType<Image>().Where(i => i.Name == "SortIconDown").SingleOrDefault();
        }
        else
            return;

        if (clearOldSortIcons != null)
        {
            Image oldSortIconUp = (clearOldSortIcons as Grid).GetVisualDescendants().OfType<Image>().Where(i => i.Name == "SortIconUp").SingleOrDefault();
            Image oldSortIconDown = (clearOldSortIcons as Grid).GetVisualDescendants().OfType<Image>().Where(i => i.Name == "SortIconDown").SingleOrDefault();
            oldSortIconUp.Visibility = System.Windows.Visibility.Collapsed;
            oldSortIconDown.Visibility = System.Windows.Visibility.Collapsed;
        }

    start:

        if (!string.IsNullOrEmpty(cp.Content.ToString()) && (string.IsNullOrEmpty(sortCheck) || sortCheck == cp.Content.ToString()))
        {
            if (hasSorted == false)
            {
                switch (cp.Content.ToString())
                {
                    case "Work Order #":
                        imgSortUp.Visibility = System.Windows.Visibility.Visible;
                        break;
                    case "Status":
                        imgSortUp.Visibility = System.Windows.Visibility.Visible;
                        break;
                }
                hasSorted = true;
            }
            else
            {
                switch (cp.Content.ToString())
                {
                    case "Title":
                        imgSortDown.Visibility = System.Windows.Visibility.Visible;
                        break;
                    case "Status":
                        imgSortDown.Visibility = System.Windows.Visibility.Visible;
                        break;
                }
                hasSorted = false;
            }
        }
        else
        {
            sortCheck = cp.Content.ToString();
            hasSorted = false;
            goto start;
        }
        sortCheck = cp.Content.ToString();
        clearOldSortIcons = sender;
        SortItems(cp.Content.ToString(), hasSorted);
        dpVideos.Source = grdVideos.ItemsSource;

Answer 1

This is because you declare the images within their own scope and use them later:

    // declare this image within the outer scope
    Image imgSortDown = null;

    if (cp.Content.ToString() == "Work Order #" || cp.Content.ToString() == "Status") 
    { 
        // declare image within the inner scope
        Image imgSortUp;

        imgSortUp = (sender as Grid).GetVisualDescendants().OfType<Image>().Where(i => i.Name == "SortIconUp").SingleOrDefault(); 
        imgSortDown = (sender as Grid).GetVisualDescendants().OfType<Image>().Where(i => i.Name == "SortIconDown").SingleOrDefault(); 
    } 

    // do more work

    imgSortUp.Visibility = true; // This wont work since the image is out of scope.
    imgSortDown.Visibility = true; // This will work since the images is still in scope.