Feeling particularly nice today? It’s possible to buy an app for a friend directly from the App Store on the iPhone.
Find the app you’d like to gift and go to its Info page. From here tap the more icon (three dots) and choose the Gift App… option from the Share sheet.
Enter the Email that the recipient uses as their Apple ID, and fill in the Message box if you want to. By default, the app will be sent immediately, but if you’re planning for a special occasion simply tap Today and use the date picker to select when you’d like it to activate.
Tap Next to send. They’ll receive an email with a link to redeem the gift.
Note: in order to gift an app to someone they must be based in the same country.