Tells the extension to prepare for a host app’s request.
- iOS 8.0+
- macOS 10.10+
- tvOS 9.0+
- watchOS 2.0+
NSExtensionobject that represents the context in which the host app makes the request. Typically, the context contains data that the extension can work on.
An extension prepares for a host app’s request by getting the context passed in this method and requesting related data items, if appropriate. This method is received after the extension is initialized, but before the principal object is asked to do anything with the context. For example, if the principal object is a view controller, it receives this message before
load is called. After an extension receives this message, the
extension property of the view controller returns a non
If your subclass conforms to this protocol and overrides
begin, the subclass is expected to call