touchesBegan not called in NSScrollView subclass until the first mouse/trackpad click on the view

Question

I subclass an NSScrollView to monitor 2-finger panning with touchesBegan/Moved/Ended. It works as long as I click on the view once after the app is launched. Then it will always work till the next time I start the app fresh.

I think I'm missing out something very obvious here. Perhaps a NSScrollView/NSView property that allows it to immediately accept touches. Can someone help?

By the way, the NSScrollView is one automatically created in Storyboard when I add a NSTableView.

Answer 1

Found the solution.

This is actually a menu bar app, so the view controller is inside a NSPopover. Showing the app in the popover does not make the app the activate app. I have to use the following line to make it active before it can respond to touches.

NSApplication.shared.activate(ignoringOtherApps: true)