Xcode

You can assign any View Controller type as a Tab to a Tab Bar Controller on a Storyboard in Xcode by performing the following steps:

1. Drag a Tab View Controller to the Storyboard
2. Drag a View Controller or for example a Tab Bar Controller to the Storyboard
3. Place the mouse upon the middle of the Tab Bar Controller
4. Keep the CTRL button pressed on your keyboard.
5. Move your mouse (with the pressed CTRL button) and the left button pressed to the middle of the View Controller you just added
6. Release the CTRL button and the mouse button
7. Now a pop up appears
8. Select the segue: Relationship Segue > View Controllers
9. Repeat step 2 to 8 to add more tabs.