Open the subject you want to send, choose Share, and Reps produces a .reps file you can pass along by AirDrop, Messages, email or a shared folder. It opens in their copy of Reps.
Sharing works one subject at a time, because a subject is the unit that makes sense to trade. Cell Biology is a coherent set of cards. A whole class usually is not.
The cards themselves, along with any photos and drawings on them. Your review history stays with you. The person on the other end starts every card new, which is correct: their schedule should be built from their own answers, not yours.
Splitting the writing is the fastest way to cover a heavy block without anyone skipping it. One person takes the antimicrobials, another takes the cardiovascular agents, and you trade files. Each of you still gets the benefit of having written your half, which is where a large part of the learning happens.
A .reps file is a snapshot. The recipient gets their own independent copy, which means they can edit and reorganise it without affecting yours, and their schedule is built from their own answers. Send an updated file if you want them to have your later version.
The recipient needs an Apple device and their own copy of Reps.
Exporting a subject before a big reorganisation gives you a complete file you can import again if you change your mind.
More answers on the help page, or write to [email protected].