How do I add launch images to my Xcode app?

In Xcode 5, launch images are stored in a folder called images.xcassets

To access this folder, click the folder icon in the project navigator and open the Images folder, then click on images.xcassets, see screenshot below.

This example is taken from VidaLingua dictionary apps. The launch images are common to all apps but the app icons are language specific which is why they appear in separate folders.

To add a launch image, make sure you it is sized correctly, then drag and drop it in on the appropriate thumbnail in the right-most panel.