reauthorizeClient

Ok, let see what you have already done. When your authentication succeeds, you're receiving DropboxAccessToken object and print it out. This object contains the actual access token, user id, refresh token, and token expiration timestamp. Unfortunately, when just printed (as you have done) it outputs only the access token string and skips everything else (incomplete data, so cannot restore it). Here you should take care to get access to everything as print everything out field by field. Once this got done you're gonna have everything needed (not just a part). I hope you don't need example for printing out of the data.

On the other side (other device), you can use available already data as something like:

let token = DropboxAccessToken(accessToken: accessToken, uid: userId,
      refreshToken: refreshToken, tokenExpirationTimestamp: expirationTimestamp)
DropboxOAuthManager.sharedOAuthManager.storeAccessToken(token)

 Again, you should already have accessToken, userId, refreshToken, and expirationTimestamp. 😉

Hope this helps.