Extensions are plug-in programs that run independently and universally across platforms. There are different types of extensions including today, share, action, and photo editing extensions. Extensions have a lifecycle and can communicate between apps and other extensions through defined APIs, but are restricted from using certain system APIs and performing long-running background tasks. Developers must use techniques like app groups and shared containers to share data between extensions and apps.

1. Extensions
Manjula Jonnalagadda

2. What are they
• Plug in programs
• Run independently
• Universal

3. Types of Extensions
• Today
• Appears in Notification centers
• Share
• Share in your app
• Action
• Change the View, Contents
• Photo Editing
• Add filters, etc
• Document Providers
• Custom Keyboards

4. Life cycle

5. Communication

6. App to Extension communication

7. APIs Unavailable
• sharedApplication
• Anything with NS_EXTENSION_UNAVAILABLE
• Access to camera or microphone
• Long running background tasks
• Receive data via AirDrop

8. Remember
• Shared frameworks cannot use restricted APIs
• Enable App groups and shared containers to share
data using NSUserdefaults, Coredata, SQLite
• Get results from webpages by using Javascript
• Perform uploads and download using
backgroundSessions
• Declare supported data types and use
NSExtensionActivationRule predicate