Launching an app in debugger mode on iOS

I have to debug an application on iOS. This application has to be built using build scripts and not XCode. So I cannot use the "build and debug" option. The pr开发者_如何学Gooblem I wish to investigate happens right at app start-up, so, attaching to the process from XCode after the app has started is not an option. Is there any way of starting an app on the device using XCode or command line if the app was not built using XCode?

---

You can launch a process on your phone and analyse it with Instruments.