Give your apps a larger reach with extensions! In this series, you’ll learn about photo extension and today extensions (also known as widgets) introduced in iOS 8. You’ll build out the extensions from starter apps to get a photo filtering extension and a today extension that tracks an RSS feed. You’ll also learn some techniques and concepts that are common across all extensions, such as app groups, sharing data, and keeping the UI lightweight. This series has been updated for iOS 9/Swift 2.
This is a companion discussion topic for the original entry at https://www.raywenderlich.com/4173-ios-app-extensions