iOS spritekit does not display nodes

import SpriteKit

classGameScene:SKScene{
    override func DidMoveToView (view:SKView) {

        //        create a sprite from an image
        let mySprite=SKSpriteNode(imageNamed: "kuri_2.png")
        //        Set Size in Size Properties
        mySprite.size = CGSize (width:20, height:20)
        //        Set in Position Properties
        // Specify the location of the image.
        mySprite.position=CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame));

        addChild (mySprite)

//        put in a rotational motion
        let action 1 = SKAction.rotateByAngle (CGFloat (90*M_PI/180), duration: 1)
//        add a moving motion
        let action 2 = SKAction.moveTo (CGPoint (x:400, y:400), duration:1)
//        Process two movements simultaneously
        let actionx = SKAction.group ([action1, action2])
//        I'm going to start moving.
        mySprite.runAction(actionx)

    }
    override functouchesBegan(touches:Set<UITouch>, withEvent:UIEvent?) {
           }

    override func update (currentTime:CFTimeInterval) {
        /* Called before each frame is rendered*/
    }
}