Xcode Swift Add black outline to SKLabelNode

I am trying to add a black border around my text, as is done in a flappy bird, but I cannot figure out how to do it quickly. I can fill in the label, but it won't let me do anything with adding a border or outline around it. Is there something I can do to add a black outline to this code?

                self.scoreLabel.fontName = "04b_19"
                self.scoreLabel.text = "\(self.score)"
                self.scoreLabel.fontSize = 80
                self.scoreLabel.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame) * 1.58)
                self.scoreLabel.fontColor = SKColor.whiteColor()
                self.scoreLabel.zPosition = 6
                self.addChild(self.scoreLabel)