How to communicate between SafariExtensionHandler and SafariExtensionViewController.xib?

I'm writing a safari app extension using the default Xcode project and objective c. I want to add interface items to the popover(as Xcode has defined it with the SafariExtensionViewController.xib) and use the SafariExtensionHandler to control and respond to these interface items.

I find that I can add interface items to the SafariExtensionViewController.xib. I also can connect those items to SafariExtensionViewController.h. However, SafariExtensionHandler.popoverViewController is a member of the SFSafariExtensionViewController class, the superClass of SafariExtensionViewController so I can not use this popover controller to access the outlets that I add to the SafariExtensionViewController. How can I access these interface items from the SafariExtensionHandler?

ChatGPT suggest I use [SFSafariApplication sharedApplication] as an intermediary. There is no such thing. Sign!

How to communicate between SafariExtensionHandler and SafariExtensionViewController.xib?
 
 
Q