Debugging iOS app built from commandline

I am building an app for iOS via commandline but I am having problems debugging it. Had I built using XCode, it wo开发者_开发技巧uld have let me "build and debug" on device without problems. But now, I don't know how to launch it on device using gdb and step through it. If I try to "add a custom target/executable" to a blank XCode project and then launch it, XCode complains about not finding the executable. Same thing happens if I install the app on device manually and try to attach to it using gdb within XCode. Any pointers on how to go about debugging this app? Changing the build process to use XCode is not an option.

This site gives a nice tutorial on how to manually set up a remote debugging session on an iOS device. The process boils down to creating a remote debugging server on the device and attaching to it with a local GDB instance.