为什么顶部和底部有边框

如何解决为什么顶部和底部有边框

我开始编写一个游戏，我想知道为什么屏幕的顶部和底部有边框

(see screenshot)

有我的代码：(GameViewController.swift)

import UIKit
import SpriteKit

class GameViewController: UIViewController {

override func viewDidLoad() {
    
    let loadingscene = GameScene(size: self.view.bounds.size)
    let skview = self.view as! SKView
    skview.showsFPS = true
    skview.showsNodeCount = true
    
    
    loadingscene.scaleMode = .resizefill

    loadingscene.size = skview.bounds.size
    
    
    skview.presentScene(loadingscene)
    
    }

}

(GameScene.swift)：

import SpriteKit

class GameScene: SKScene {
    
    let loadingImage = SKSpriteNode(imageNamed: "loadingimage")
    
    override func didMove(to view: SKView) {
        
        loadingImage.anchorPoint = CGPoint.zero
        loadingImage.position = CGPoint.zero
        loadingImage.size = self.size
        loadingImage.zPosition = -1
        self.addChild(loadingImage)
        
    }
}

背景分辨率为1170 × 2532

感谢所有提供帮助的人:)