: iOS will not run modified code unless it is "signed" with a valid certificate. This is the most critical step for getting a modded app to actually open on your device. Popular Tools for Installation

to edit the app's executable code to bypass checks or unlock features. Tweak Injection : Injecting dynamic libraries ( files) that run alongside the app to add new functionality. 3. Repacking and Signing

Why do people go through this complex process? The motivations fall into three categories: