Could not find a storyboard named 'MainStoryBoard' in bundle NSBundle

The simulator is not case sensitive, but the device is. If your storyboard is called MainStoryboard, not MainStoryBoard, this will cause your problem.

I have fixed this issue by following below steps:

Renaming "MainStoryboard.storyboard" to "MainStoryboard_1.storyboard"

Open file "$your_app$-Info.plist" located in "Supporting Files" folder. Edit "Main storyboard file base name" to "MainStoryboard_1.storyboard".

Rerun the app, and it worked for me.

I renamed my storyboard file back to its original "MainStoryboard.storyboard".

Edited the .plist file back to its original.

Rerun the app, and it worked for me.
For some reason the file "MainStoryboard.storyboard"
was not recognised after force quitting Xcode and following above steps made the app recognise the file back again.