Note: This documentation is for version 1. For the latest features, please see the version 2 documentation. If you have yet to upgrade, see the upgrade guide.
Config iOS
How to Set the App Icon
Click Assets.xcassets in the Project navigator and then choose AppIcon.
Now just drag the right sized image (in .png format) from Finder onto every blank in the app set. The app icon should be all set up now.
Referential https://stackoverflow.com/questions/28170520/ios-how-to-set-app-icon-and-launch-images