iOSToolButton.Constructor(type As Types, title As Text = "", image As iOSImage = Nil)

From Xojo Documentation

Constructor
iOSToolButton.Constructor(type As Types, title As Text = "", image As iOSImage = Nil)

Creates a button with the specified type, title or image.

Sample Code

Adds the SystemRefresh icon as a toolbar button:

Dim tb As New iOSToolbutton(iOSToolbutton.Types.SystemRefresh)
Self.Toolbar.Add(tb)