How to create a tweak for jailbroken iPhone

My question is... Can we use Xcode to create a tweak 开发者_运维技巧for jailbreaked iPhone? Foe example if I want to add some button in the lock screen how can I do? How can I mod the GUI of the default iPhone applications?

This is a really old question, but David is actually incorrect on most counts.

You can add custom UI to jailbroken devices, create tweaks without Xcode, hook into anything you wish, and more, without even having the source code for SpringBoard or wishing for it to be extensible.

MobileSubstrate is a code replacement platform that literally allows you to do anything. You don't even need to be an expert, but admittedly, having at least a moderate grasp on programming and Objective-C concepts helps a lot.

What you're talking about cannot be done. You're assuming 1) that you will have the source code for Springboard (lock screen), and 2) that those programs are extendable.

Without having the source code (it's proprietary), you cannot make "Tweaks" to the lock screen. You have nothing to compile into the lockscreen.

While you can mod them by editing the internal plists (simple things like show title bar or disable rotation), you will not be able to add functionality using XCode.

To create "tweaks" you would have to rewrite the lock screen entirely, or insert very low-level hooks into the Springboard/iOS. This is not possible via Xcode alone, since Xcode is not capable of even installing iOS-level apps (all installed apps are user-level).

You need expert knowledge of the private framework calls, and possibly be capable of disassembling and reverse engineering the specific program you're trying to extend.