'Too many open files' error xcode

Check if you have too many open simulators. I closed all the simulators and the error went away

I think you just have reached the maximum number of open file descriptors.

You can check the limit by

$ ulimit

And change it by:

$ ulimit -n 6666

But do not forget ulimit changes the limit only for current session. You have to put ulimit -n 6666 to .bash_profile or something like this