Your comments

Working Copy iOS app does a good job at that at the moment. There's some integration in Textastic for Working Copy but it's not as seemless as other integrations (even Dropbox), you have to go file by file and can't commit/push or anything from within Textastic, so there's a lot of app switching. If you've got gestures on, it might not be too bad, but dealing with the crashes between the two can prove irritating.

I'd throw lots of Kickstarter / IndieGoGo money on this, and/or an in-app purchase, even for just interacting with a GitHub repo, that's worth it on it's own. GitHub I'd say has the easiest reach (since I believe there's an API for it all, not just Git commands), and could be further modified to implement Git / SVN on their own, as soon as capabilities / libraries are made compatible.

I support the author either way, this is still hands down the best code app for iPad! Keep on keeping on, such a big fan!

I'd love to see GitHub/Git or SVN, I'd pay extra for that (in-app purchase) if it was necessary!
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I'd really like to see this too, there's a huge lack of support for GitHub on iOS, baking some sort of GitHub and/or SVN commit features would really be awesome, but I know that as simple as it sounds - making it happen for iOS and Textastic specifically will be quite a challenge for the developer.

If GitHub support is considered, I'd be willing to pay a premium for it, like an in-app purchase, so keep that in mind in case you want to add targeted features like that but not have to raise your whole app price.