Localising by adding new languages is all well and good, but for a really polished experience you'll want to consider more than just the words. With this in mind, I really liked Roy Marmelstein's article (and the associated library PhoneNumberKit) about parsing international phone numbers.
It's not brand new but I came across this implementation of Reachability in Swift this week via Little Bites of Cocoa, which remains a fantastic resource. Anyway, if you're looking for a modern way to keep up to date on the network status, this library by Ashley Mills looks good.
There has been plenty written on this subject, but this week Andrew Bancroft summed up some of the pros and cons of bringing that shiny new library into your app. Mentioned in the article, but also deserving of a special mention, the CocoaPods quality index is a really quick way to see roughly what kind of shape a library is in before even considering it.