Dev:Updating extensions for iOS 12

Let's collect knowledge like we did with iOS 11, iOS 10, iOS 9, iOS 8 and iOS 7 – paste in your notes and share what you've learned, and somebody else will organize it later. :) If you want to ask questions and share tips over chat with other developers, see How to use IRC for how to connect to #theos and #iphonedev.

'''Hey developer, you can add your knowledge here! Yes, you! Make an account and edit this page!'''

If you want to see what's been recently updated on this page, you can use the wiki's history feature to compare the revisions (to look at the diff) since the last time you visited this page.