Question

I have a user control in my project and I want when I click on a button to add this user control to a form, but if the user control is already in the form I want to show it.

This the code I wrote so far:

Using GstAbonnement As New GestionAbonnement
            GstAbonnement.Dock = DockStyle.Fill
            Me.Controls.Add(GstAbonnement)
End Using

How can I test if the user control is already in the form or not ?

Answer 1

With your current code, that control will never be found in the form because the Using...End Using syntax with dispose of the control.

Try changing it to this:

Dim GstAbonnement As New GestionAbonnement
GstAbonnement.Name = "gestionAbonnement1"
GstAbonnement.Dock = DockStyle.Fill
Me.Controls.Add(GstAbonnement)

Notice I supplied a name for the control.

Now you can simply check the key if the control was in the collection or not:

If Me.Controls.ContainsKey("gestionAbonnement1") Then
  Me.Controls("gestionAbonnement1").Visible = True
  Me.Controls("gestionAbonnement1").BringToFront()
  MessageBox.Show("Found!")
End If