Invoke beginDraggingSession programmatically in NSView

NSView+Drag.swift

class NSView {
    override func mouseDown(with event: NSEvent) {
        guard event.clickCount <= 2 else { return }
        
        let location = view.convert(event.locationInWindow, from: nil)
        let eventMask: NSEvent.EventTypeMask = [.leftMouseUp, .leftMouseDragged]
        let timeout = NSEvent.foreverDuration
        var dragInitiated = false

        view.window?.trackEvents(matching: eventMask, timeout: timeout, mode: .eventTracking, handler: { (event, stop) in
            guard let event, event.clickCount <= 2 else { return }
            if event.type == .leftMouseUp {
                stop.pointee = true
                if event.clickCount == 2 {
                    // Double Click
                }
                if event.clickCount == 1, !dragInitiated {
                    // Single Click
                }
            } else {
                let movedLocation = view.convert(event.locationInWindow, from: nil)
                if abs(movedLocation.x - location.x) > dragThreshold || abs(movedLocation.y - location.y) > dragThreshold {
                    stop.pointee = true
                    dragInitiated = true
                    
                    var draggingItems = [NSDraggingItem]()
                    // ...
                    beginDraggingSession(with: draggingItems, event: event, source: self)
                }
            }
        })
    }
}