Possible reasons for signal 11 in iOS ARC

Currently my third-party crash report service shows that the number one crash is "signal 11 is raised" on all kinds of device and system version. I searched a bit about signal 11 and learned

It's a segmentation fault, your app trying to access a non-initialized / already deallocated region of memory

from here

My question is what are possible reasons for signal 11 happened in arc? is it misuse of blocks somewhere?

P.S. The third-party crash report didn't provide crash log for "signal 11 is raised" and I can't reproduce the crash myself yet