swift - Animation reversing for View X value in animateWithDuration

Question

Why would this alpha in the blur view, but take the gameView, move it off scree and then animate back on the screen?

UIView.animateWithDuration(0.5, animations: {

        blurView.alpha = 1

        // slide containers around
        self.gameView.center.x = self.view.bounds.width
    })

I thought I was giving the end point of the animation?

It's almost reversing the center x value. Instead of sending it off screen, it’s bringing it back on to the screen. I want to move the UIView off the screen, not move it out and then slide it back into view.