Can macOS Safari App Extensions be purged for example in low memory situations?

I'm building a safari app extension with objective c. I'm using the default Xcode project. I've successfully added a NSView to the popover window. When I drag a NSTableView into the popover window, it appears in the XIB, but I can't find how to connect it to the SafariExtensionViewController. I tried adding a custom ViewController to the XIB and making the tableview its view which seems to be ok. How should I proceed from here, or is their another approach?

When calling:NSURL* aURL = [NSURL URLByResolvingBookmarkData:secBookmark options:options relativeToURL:nil bookmarkDataIsStale:&isStale error:&err];isStale is YES.When attempting to get a fresh bookmark, calling:NSData* secureBookmark = [aURL bookmarkDataWithOptions:options includingResourceValuesForKeys:nil relativeToURL:nil error:&err];produces:2019-03-11 15:53:51.603133-0700 XXX[534:8439] Error: Error Domain=NSCocoaErrorDomain Code=256 "Could not open() the item" UserInfo={NSURL=file:///Users/oldmancoyote1/Desktop/E%20Projects%20folder/Drawing/Drawing%201%20.pdf, NSDebugDescription=Could not open() the item}If I ignore isStale, there appears to be no problem. Can I safely ignore isStale?

I'm trying to get the row index of a NSTableRowView that has experienced a mouseEnter event. It should be easy with rowAtPoint using NSEvent.locationInWindow. I can't get it to work. The NSTableView lies inside a NSStackView. Of course the NSStackView adjusts the visual size of the NSTableView etc. Is NSStackView interfering? If so, how should I adjust my call to rowAtPoint?

As far as I can determine, there is no way to save the data in my Safari App Extension when Safari terminates. It seems I have to save the data every time the page changes. That's wasteful. Does anyone know of a work around?

My Safari App Extension is having trouble with one website. This is typical for some other websites as well. Navigating to that website results in 6 “Load” events. For each such event I send a “safari.extension.dispatchMessage” to my objC code. For the first of these Load messages, my objC code sends a ‘sendMeIcons” message to “safari.self.addEventListener('message', function(event)”. The other 5 Load events are ignored by my objC code and do not send this message. safari.self.addEventListener('message', function(event) receives sendMeIcons JUST once. Yet, the event handler for this message) is invoked 4 times. The first invocation is correct. The other 3 are spurious. I have no idea why this is happening. Here is my objC code safari.self.addEventListener('message', function(event) { if (event.name === "Load My URL") { console.log('In event listener Load My URL'); ... return; } if (event.name === "sendMeIcons") { ... if (hrefs.length <1) //THIS IS ALWAYS TRUE FOR THIS TEST CASE. { safari.extension.dispatchMessage("js Found No Icons"); return; } else { ... safari.extension.dispatchMessage("IconsReturned",{"urls": arrayOfUrls}); return; } } I don't have a clue how to proceed. Any suggestions.