How can I replicate the process that works for https://extensify.io?

English Only
1

extensify works great by installing a certificate on my iOS device, then downloading the signed binary from the App Store, then uploading the binary to their backend server, then resigning the patched binary and finally installing it on my iOS device with the patches.

I want to know how this process works, a step by step if you will.

Does anyone knows where / what I should be searching to figure it out?

Thanks!

2

Resign, resign never changes.

Google:
optool
iOS Resign

3

It’s not the resign part that got my curiosity but rather the tool that is installed on the iOS device.

This tool (3rd party app) is able, all while running on the iOS device to:

  1. Download an App from the App Store
  2. Upload it to a 3rd party server
  3. Download from a 3rd party server and install an app on the device.

All this without jail break… what I’m interested is downloading app and examining them without jail breaking my iPhone, and I’m interested in understanding how this tool does it so that I can repeat the process for my toolchain.