hello can you tell me if i woukd need a usb adapter for a rose gold macbook air bought this year

You would need a USB-C to USB adapter if you need to connect USB devices that use the larger connector rather than the smaller USB-C port on the MacBook Air.

Otherwise, you would need to tell us why you think you may need the adapter as we don't know what needs you specifically have.

If you mean the newer version macbook air, then yes. Will need to buy usb-c.. But if you have the device look at the side ports.

Aside from the ports, you cannot transfer apps from an iDevice to a computer - the apps would not work as they are for iOS and the computer runs on Mac OS. You can only create backups from the phone.

babowa is indeed correct. iPhone apps don't work on Macs.

You can connect the iPhone to the Mac to transfer music, photos, files, movies to the iPhone from the Mac however.