I Meet the same problem
Same problem here...
Custom font (San Francisco Text Light) works fine in the whole app except the launch screen xib. In IB it looks good but when the app lanuches (in simular or device) it has different font in the luanch screen.
The big problem is the lack of documentation about launch storyboards and their limitations. Weird thing is that images from asset catalog are loaded fine so they can be used but custom fonts are different story - why? I saw a few filled radars about using custom fonts in launch storyboards but it's hard to say if it's bug or not.
Anyway - launch storyboard has a lot of limitations and therefore there is a lot of situations when is better to use launch images instead. That's sad :-/