Extension: Easily set NSView background color

NSView+BackgroundColor.swift

extension NSView {
  var backgroundColor: NSColor? {
    get {
      if let colorRef = self.layer?.backgroundColor {
        return NSColor(cgColor: colorRef)
      } else {
        return nil
      }
    }
    set {
      self.wantsLayer = true
      self.layer?.backgroundColor = newValue?.cgColor
    }
  }
}

Usage Example

override func viewDidLoad() {
  super.viewDidLoad()
  view.backgroundColor = .clear   // .white ? .black
}