I'm looking to possibly build an iOS app where I would need to get a list of friends of the logged in user who are also using the app and then loop over that list to get an even bigger list of their friends who are also using the app. Hopefully the little scenario below will better illustrate what I mean if it's not clear
Lets say "Sam" uses my app and he has 400 friends of which 30 are using my app. I would like to loop the 30 friends who are using the app to get their friends list so lets say the first person of the 30 is "Jake" and he has 10 friends who are also using the app they should be added to an array and then the next person in the 30 people loop is "Jen" and she has 15 people using the app they would be added to Jake's 10 friends and so on.
I know it's possible according to this link Get a list of friends of a friend on Facebook to get the friends list of a friend but my main concern is speed. Do you think getting a list of friends of friends would take too long for a user of the iOS app?