Fun fact: years ago I started building an ipad app for Github, but it was rejected multiple times by Apple because users could use it to create a new account but then Apple wouldn't get any commission.
I have an iPhone app in the store (been there for a while) and it has yet to run into approval issues. FWIW, I don't allow sign-ups from within the app (or direct users to their website to sign up) - I expect users to already have an account.
What do you mean Apple wouldn't get any commission? For creating new GitHub accounts? Am I missing something?
I think what ocscardelben meant was that Apple wouldn't get any commission off of new, paid, GitHub accounts.
YES
Apple wants devs to use in-app purchase to sell things in apps . If you don't they don't get their 30% cut of all sales. It's the same reason Amazon can't sell books in the Kindle app, they have to direct users to the website.
It's the same problem Dropbox had a while back. Apps using the Dropbox SDK (including the main Dropbox app) showed an interface where you could log into your Dropbox account or click a button to let you sign up for one. Since Dropbox has some paid account plans (like GitHub), Apple decided that this functionality violated its rule stating that all spending that takes place inside the app must happen using the In-App Purchase API so that Apple can get its 30%.
Since GitHub charges based on a monthly subscription, you can't have an app that charges for a service without going though Apple's In-App Purchase program.