My app crashes several times without any error or stack trace on my console. Then the only way left is to go and check Apple’s crash reporter. I found “jettisoned” next to my app name, which in turn implies iOS killed my app, but how do I figure out why did it happened? Why is iOS killing my app? Initially, I thought it was a memory overflow issue, but then, using Instruments, I figured out that my app was taking hardly 4-5 MB of memory, so I discarded those issues. Apple’s doc does not mention much about this. Any help or suggestions would be highly appreciated.

It means the process was terminated because iOS needed memory:
I would take a look at that technical note for some additional help. The documentation also points out the Instruments does not measure graphics memory use, and that requires special handling.