MouseTrackingView.swift

public class MouseTrackingView: NSView {
    
    public var callback: ((Bool) -> Void)?
    
    private var trackingArea: NSTrackingArea?
    
    public override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }
    
    required init?(coder decoder: NSCoder) {
        super.init(coder: decoder)
        commonInit()
    }
    
    fileprivate func commonInit() {
        updateTrackingAreas()
    }
    
    override public func updateTrackingAreas() {
        super.updateTrackingAreas()
        if let trackingArea = trackingArea {
            removeTrackingArea(trackingArea)
        }
        
        trackingArea = NSTrackingArea(rect: bounds, options: [.activeInKeyWindow, .mouseEnteredAndExited], owner: self, userInfo: nil)
        addTrackingArea(trackingArea!)
    }
    
    override public func mouseEntered(with event: NSEvent) {
        super.mouseEntered(with: event)
        callback?(true)
    }
    
    override public func mouseExited(with event: NSEvent) {
        super.mouseExited(with: event)
        callback?(false)
    }
    
    
}