How in the world did you managed to use storyboard? I hate using it for moderate-complex UI apps. This guy say it better than me on why I hate storyboard (especially the first reason):
I use it in combination with programmatic UI for more complex things but find it's so much easier and faster when doing auto layout to just use storyboards.
The real reason for which i stopped using them is that it doesn't work well with git. As soon as you've got more than one people in the team, it's over.
It is actually a solvable problem if you're willing to dig into the details of the file changes. It isn't pleasant, but welcome to life. Team members can make conflicting changes as long as someone is willing to dig through the mud to make them all agree with each other. I've been doing it personally for a long time, it isn't my favorite part of the job but it does enable significant parallel productivity.
https://www.youtube.com/watch?v=g6yz5oX5iWc
FWIW, if you like and good at it, more power to you.