If you’re completely bored by gray-backgrounded NSWindow and wondering how to improve the UI with some colors, here we go with some helps. I highly recommend Luka Kerr’s post on Github. We will build this: final

Step 1. Create a project in XCode with Swift and Storyboard. create

Step 2. Add a new NSWindowController.swift file to the project add

Step 3. Connect the new custom controller with Storyboard element connect

Step 4. Add some code to our CustomWindowController.swift

override func windowDidLoad() {
    func configureWindowAppearance() {
        if let window = window {
            if let view = window.contentView {
                view.wantsLayer = true
                view.layer?.backgroundColor = NSColor.white.cgColor

If we run our app, we’ll see the following, still ugly but at least the background is white now… firstrun

We don’t need the Window title, so we add configureWindowAppearance() method the following:

    window.titleVisibility = .hidden

Step 5. Add a CustomView on Storyboard to our ViewController and add an NSView Cocoa class file. customview addnsviewclass

Don’t forget to add our new file to our CustomView. connectview

Run again our app to check, where we are. Not bad, but can be much-much better. secondrun

Step 6. Remove titlebar, since can draw nicer controllers. There are two ways to do it.

  1.  window.styleMask.remove(.titled)

    It seems to work, but actually not. I will show you later, this code will break your NSTextField.

  2.  window.styleMask.remove(.closable) // close button (red)
     window.styleMask.remove(.miniaturizable) // miniaturize button (yellow)
     window.styleMask.remove(.resizable) // resize button (green)
This code removes the buttons but titlebar stays there, so add these two lines more:

    window.titlebarAppearsTransparent = true


Step 7. Add an Image button to the Storyboard, then create a new NSButton class and connect them. nsbutton

You will need 3 versions of the button image. ![custombutton](/images/Custom close button.png)

Export the images one-by-one as .pdf and add to project assets.

Step 8. Jerry Shan made an excellent video about custon NSButton. After watching it, add the following code to your CustomCloseButton.swift

var mouseIsInside = false
    override func awakeFromNib() {
    self.image = NSImage(named:"Custom close button")
        let trackingArea = NSTrackingArea(rect: self.bounds, options: NSTrackingArea.Options(rawValue: 129), owner: self, userInfo: nil)
    override func mouseEntered(with event: NSEvent) {
    self.image = NSImage(named:"Custom on-mouse close button")
        mouseIsInside = true
    override func mouseExited(with event: NSEvent) {
        self.image = NSImage(named:"Custom close button")
        mouseIsInside = false
    override func mouseDown(with event: NSEvent) {
    self.image = NSImage(named:"Custom pressed close button")
    override func mouseUp(with event: NSEvent) {
        if mouseIsInside {
        } else {
            self.image = NSImage(named:"Custom close button")

Step 9. Run the code for the final result. final

Source code: Github