iTunesArtwork png files needed in xCode 5?
Some time ago you were supposed to include your icon in large format 512x512 and 1024x1024 in your bundle when submitting an app to the AppStore, But after some changes in Xcode and iTunesConnect this is no longer necessary, you upload these two files directly to iTunes Connect and are not required in your bundle anymore.
The iTunesArtwork file is still used in AdHoc (and enterprise) distribution according to the official Apple documentation:
https://developer.apple.com/library/content/qa/qa1686/_index.html
It is (as Ponchotg says) not necessary for appstore builds.
Go to
Your xcode Project > Resources > App Icons
Rename following images1. iTunesArtwork.png to iTunesArtwork 2. iTunesArtwork@2x.png to iTunesArtwork@2x