How can I replace level button image with a screen

I know how to take and save a screenshot to the photo library. I do this using the code below. I would like to replace my level scene button images with screenshots of my gameScene. Say my image buttons are 150x150. How can I achieve this?

    func takeScreenShot(scene:SKScene)  {
    let bounds = self.scene!.view?.bounds
    UIGraphicsBeginImageContextWithOptions(/*CGRect(x: 0, y: 0, width: 100, height: 100).size*/bounds!.size, true, UIScreen.main.scale)
    self.scene?.view?.drawHierarchy(in: bounds!, afterScreenUpdates: true)
    let screenshot = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    UIImageWriteToSavedPhotosAlbum(screenshot!, nil, nil, nil)

}


class LevelSelectScene: SKScene {

let button1: SKSpriteNode = SKSpriteNode(imageNamed: "image1")
let button2: SKSpriteNode = SKSpriteNode(imageNamed: "image2")
let button3: SKSpriteNode = SKSpriteNode(imageNamed: "image3")

                    ...

override init(size: CGSize){
super.init(size: size)

button1.position = CGPoint(x: self.frame.width/4, y:  self.frame.height/2)
self.addChild(button1)

button2.position = CGPoint(x: self.frame.width/2, y:  self.frame.height/2)
self.addChild(button2)

button3.position = CGPoint(x: 3*self.frame.width/4, y:  self.frame.height/2)
self.addChild(button3)

}

As UIGraphicsGetImageFromCurrentImageContextreturns a UIImage, and SKTexture has an initiaser that takes a UIImage, and SKSpriteNode (which I assume you are using for your button) has an initialiser that takes an SKTexture and a CGSize, I think you have everything you need:

if let screenshot = UIGraphicsGetImageFromCurrentImageContext() {
   let screenShotTexture = SKTexture(image: screenshot) 
   let button = SKSpriteNode(texture: screenShotTexture, size: CGSize(width: 150, height: 150))
}

Using this, you wouldn't need to save the screenshot to the photo album (unless you wanted to for other reasons).