In Xcode, you can open a file in various ways, you can open a file in the standard editor, in a new or existing assistant editor, in a new or existing tab, or in a new window. Here's how you can decide about this. When you clicking on a file name, hold down ⇧ + ⌥ + ⌘.A pop-over will appear and let you choose where exactly you want this file to be displayed. Demo Video -