On Xcode 6.3.1 I created a launch screen for my app with the same initial ViewController for the app.
The problem is that when the app is launched all the fonts have a slightly different size.
I'm using the Headline and Caption 1 text styles on the labels.
There are some pictures below to make the problem clearer.
Thanks!
Launch screen:
Main Storyboard initial view controller:
The difference is noticeable when superimposing both images: