When an iOS app is stopped/restarted from Xcode, it often jumps to the main.m file to show that the app has received a SIGKILL signal. It’s a very distractive behavior when you’re working on something and want to have a quick test.

How to fix: edit your ~/.gdbinit file so that it has these lines:

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set start-with-shell 0
handle SIGKILL nostop noprint nopass

Source: stackoverflow