How to change the duration of a movement with count- Swift SpriteKit?

in my game there's a class for a "wall" that's moving to the left. I want to change the speed of it based on count i put in a touchesBegan class:

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {

    count++

}


func startMoving() {

        let moveLeft = SKAction.moveByX(-kDefaultXToMovePerSecond, y: 0, duration: 1 )

        let move = SKAction.moveByX(-kDefaultXToMovePerSecond, y: 0, duration: 0.5)

        if(count <= 10)
        {
            runAction(SKAction.repeatActionForever(moveLeft))
    }

    else
        {
        runAction(SKAction.repeatActionForever(move))
    }

but it's not working. can you help?