编辑占位符在源文件中

Question

我不明白这里的问题，我的代码没有错误，但是当我点击运行时，模拟器上没有任何内容。我需要帮助，如何在模拟器上看到我的图像显示为Scrollview？

import UIKit

class ViewController: UIViewController {

    @IBOutlet var mainScrollView: UIScrollView!
    var imageArray = [UIImage]()


    override func viewDidLoad() {
        mainScrollView.frame = view.frame
        super.viewDidLoad()
        imageArray = [#imageLiteral(resourceName: "IMG_1750"), #imageLiteral(resourceName: "IMG_1754")]
        for i in 0..<imageArray.count{
            let imageView = UIImageView()
            imageView.image = imageArray[i]
            imageView.contentMode = .scaleAspectFit
            let xPosition = self.view.frame.width * CGFloat(i)
            imageView.frame = CGRect(x: xPosition, y: 0, width: self.mainScrollView.frame.width, height: self.mainScrollView.frame.height)
            mainScrollView.contentSize.width = mainScrollView.frame.width * CGFloat( i + 1)
            mainScrollView.addSubview(imageView)
        }


    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}