设置游戏视图控制器的背景

Question

我想更改游戏视图控制器的背景， 但是，例如经典的self.view.backgroundColor = UIColor.red无法正常工作，我不确定为什么。有人可以帮我吗？也许我缺少一些简单的东西，这里是一些代码

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.backgroundColor = UIColor(red: 35/255.0, green: 35/255.0, blue: 33/255.0, alpha: 1.0)




    codedLabel.frame = CGRect(x: 100, y: 100, width: 200, height: 200)
    codedLabel.textAlignment = .center
    codedLabel.text = "Box and Weave"
    codedLabel.numberOfLines=1
    codedLabel.textColor=UIColor.white
    codedLabel.font=UIFont.systemFont(ofSize: 25)
    codedLabel.backgroundColor = UIColor(red: 35/255.0, green: 35/255.0, blue: 33/255.0, alpha: 1.0)

    self.view.addSubview(codedLabel)
    codedLabel.translatesAutoresizingMaskIntoConstraints = false
    codedLabel.heightAnchor.constraint(equalToConstant: 200).isActive = true
    codedLabel.widthAnchor.constraint(equalToConstant: 200).isActive = true
    codedLabel.centerXAnchor.constraint(equalTo: codedLabel.superview!.centerXAnchor).isActive = true
    codedLabel.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100).isActive = true




    playButton.translatesAutoresizingMaskIntoConstraints = false
    playButton.backgroundColor = UIColor.white
    playButton.setTitle("Play!", for: .normal)
    playButton.setTitleColor(UIColor.blue, for: .normal)
    playButton.titleLabel!.font =  UIFont(name: "HelveticaNeue-Thin", size: 23)
    playButton.titleLabel?.adjustsFontSizeToFitWidth = true
    playButton.titleLabel?.minimumScaleFactor = 0.5
    playButton.layer.cornerRadius = 25
    self.view.addSubview(playButton)
    // contraints for button
    let buttonHeight = playButton.heightAnchor.constraint(equalToConstant: 50)
    let buttonWidth = playButton.widthAnchor.constraint(equalToConstant: 125)
    let xPlacement = playButton.centerXAnchor.constraint(equalTo: self.view.centerXAnchor)
    let yPlacement = playButton.centerYAnchor.constraint(equalTo: self.view.centerYAnchor)

    buttonConstraints = [buttonHeight, buttonWidth, xPlacement, yPlacement]
    NSLayoutConstraint.activate(buttonConstraints)
    playButton.addTarget(self, action: #selector(playButtonMethod), for: .touchUpInside)

}

This is how it looks when loaded