I've installed REActivityViewController as a pod. Here's the picture of the Resourcesfolder in the pod:

And here's one of the lines trying to pull the strings:
[_cancelButton setTitle:NSLocalizedStringFromTable(@"button.cancel", @"REActivityViewController", @"Cancel") forState:UIControlStateNormal];
The button titles come out not-localized. In this example it shows button.cancel. It's also not just this button title but all the buttons in this dependancy.
EDIT
So in my Main Project under Info there's this. I can't click it to see what files those are. I have NSLocalizedStrings in my main project but I have yet to create a .strings files out of them:

EDIT
So I checked my Pods-resources.sh and found this:
install_resource "REActivityViewController/REActivityViewController/REActivityViewController.bundle"
install_resource "REActivityViewController/REActivityViewController/Localizations/de.lproj"
install_resource "REActivityViewController/REActivityViewController/Localizations/en.lproj"
install_resource "REActivityViewController/REActivityViewController/Localizations/fr.lproj"
install_resource "REActivityViewController/REActivityViewController/Localizations/it.lproj"
install_resource "REActivityViewController/REActivityViewController/Localizations/ru.lproj"
install_resource "REActivityViewController/REActivityViewController/Localizations/uk.lproj"
install_resource "REActivityViewController/REActivityViewController/Localizations/zh-Hans.lproj"
