I’ve made three posts that explains you how to begin in iOs jailbreak development and I gave you some code to do basics tweaks. If you want to continue and go further, you can go and see some other source code. There’s a website where you can find a lot of source code, this is TweakWeek.
To see the source code, just click on one tweak and you’ll be on GitHub. Then click on the Tweak.xm file and you’ll have the source code 🙂 .
You can find the source code of some tweak of the french developer M_Vincent_M on his website : Vincentmm.free.fr
I hope that it had helped you.