编码SpriteKit游戏，我收到“不能在类型'CGRect上使用实例成员'minX'”

我无法通过CGRect.minX / Y和CGRect.MaxX / Y修复此错误消息。错误“无法在类型'CGRect上使用实例成员'minX'”。我该如何解决？

func spawnNewDisc(){

    var randomImageNumber = arc4random()%4
    randomImageNumber += 1

    let CheeseBlock = SKSpriteNode(imageNamed: "CheeseBlock\(randomImageNumber)")
    CheeseBlock.zPosition = 2
    CheeseBlock.name = "CheeseObject"

    let randomX = random(min: CGRect.minX(gameArea) + CheeseBlock.size.width/2,
                         max: CGRect.maxX(gameArea) - CheeseBlock.size.width/2)

    let randomY = random(min: CGRect.minY(gameArea) + CheeseBlock.size.height/2,
                         max: CGRect.maxY(gameArea) - CheeseBlock.size.height/2)

    CheeseBlock.position = CGPoint(x: randomX, y: randomY)
    self.addChild(CheeseBlock)

}