SK subview color doesn't change to it's .backgroundColor

Question

I am trying to make an overlaying view which just makes the screen turn red. However, even if I set the background color to any color, it just shows as gray. I can still maneuver it around the screen, I just can't change the color for some reason.

Here's what I put into my didMove to view function:

let pulseView = SKView(frame: self.view!.frame)
pulseView.backgroundColor = SKColor.red
pulseView.alpha = 1
self.view?.addSubview(pulseView)