Error in Swift code : first time playing about with Xcode.
I get an error when trying to run my project, the error is as follows.


Type CGFLoat has no member "random" 

    var randomPosition = CGFloat.random (min: -200, max: 200)
        wallPair.position.y = wallPair.position.y +  randomPosition
        wallPair.addChild(scoreNode)

thanks in advanced