Simply redeem the card in the App Store or Apple Music app . The funds are added to your Apple Account balance , which automatically covers apps, subscriptions, and iTunes media.
Some users have successfully exchanged or used these cards at physical Apple Store locations to facilitate a switch, though this is subject to current store policy. Important Safety Note Apple Gift Card buy itunes card with apple store gift card
Depending on which card you have, you can convert its value into usable credit for apps and music: Simply redeem the card in the App Store or Apple Music app
You may call Apple at 1-800-MY-APPLE to request a balance transfer from the store card to an iTunes/App Store code. which automatically covers apps