So you’ve just finished your app and now it’s time to create your app icons. You could open Photoshop, create your 512×512.png icon, re-size it to 72×72, save as a new name, re-size, save as, etc. or you could use Icon Robot for free and save a lot of time.
First go to Icon Robot’s website where you can download the iOS and Android icon software for free from their Drop Box links. Install Icon Robot and open it.
If you’ve created an iOS app and you already have your 512×512.png for the App Store, locate that file.
Then drag your image to Icon Robot and it will automatically re-size and create the other sizes for you.
Choose the folder where you want them to be saved and there you go, all of your iOS icons properly sized and named for iTunes.