Gaurav S Tomar: Extensions in iOS

Not all but most of the APIs are available for extesions
Extensions have separate container for them which means they act like a saperate app for there parent app
Extensions don't have access to their parent app data but can opt into data sharing
Apps and Extensions can use a shared container/storage area which can be accessed at same time with the help of;
- NSFileCordination - provides general syns strategy for app and extension
- CoreData
- sqilite
- NSUserDefaults - with a shared suite name
- Shared Keychains - for an app group
Once user approve the Privacy access (e.g; Photos, Location..) to an app all its extensions don't need to ask saperately
Extensions are stateless that means they are killed aggressively

Extensions configuration keys in .plist

NSExtension - A dictionary of keys and values that describe an app extension
- NSExtensionPointIdentifier - Extension point’s reverse DNS name PFB
- NSExtensionPrincipalClass - The name of the principal view controller class created by the template
- NSExtensionAttributes - A dictionary of extension point–specific attributes that specify aspects of an app extension
  - further configuration based on extension kind

Values for the NSExtensionPointIdentifier key based on extension type;

Gaurav S Tomar