如何在分页UIScrollView中显示已确定的项，而不是仅从0加载它

import UIKit

class ViewController: UIViewController, UIScrollViewDelegate {
    let scrollView = UIScrollView()
    let pageSize = CGSize(width: 320, height: 480) // 每页的大小
    let itemCount = 10 // 内容数量
    var totalPages = 0 // 总页数
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        scrollView.frame = view.bounds
        scrollView.delegate = self
        scrollView.isPagingEnabled = true
        view.addSubview(scrollView)
        
        // 计算总页数
        totalPages = Int(ceil(Double(itemCount) / Double(pageSize.width / pageSize.height)))
        
        // 添加每一页的内容视图
        for pageIndex in 0..<totalPages {
            let pageView = UIView(frame: CGRect(x: CGFloat(pageIndex) * pageSize.width, y: 0, width: pageSize.width, height: pageSize.height))
            pageView.backgroundColor = UIColor.random // 自定义视图的背景颜色，可以根据实际需求进行修改
            
            // 添加内容到每一页的视图中
            let startIndex = pageIndex * Int(pageSize.width / pageSize.height)
            let endIndex = min(startIndex + Int(pageSize.width / pageSize.height), itemCount)
            for itemIndex in startIndex..<endIndex {
                let itemLabel = UILabel(frame: CGRect(x: 0, y: CGFloat(itemIndex - startIndex) * pageSize.height, width: pageSize.width, height: pageSize.height))
                itemLabel.text = "Item \(itemIndex)"
                itemLabel.textAlignment = .center
                pageView.addSubview(itemLabel)
            }
            
            scrollView.addSubview(pageView)
        }
        
        // 设置UIScrollView的contentSize以适应所有内容的大小
        scrollView.contentSize = CGSize(width: CGFloat(totalPages) * pageSize.width, height: pageSize.height)
    }
    
    // 监听UIScrollView的滚动事件
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        let pageIndex = Int(scrollView.contentOffset.x / pageSize.width)
        print("当前页数：\(pageIndex + 1)")
    }
}

// 随机生成颜色的扩展
extension UIColor {
    static var random: UIColor {
        return UIColor(red: .random(in: 0...1),
                       green: .random(in: 0...1),
                       blue: .random(in: 0...1),
                       alpha: 1.0)
    }
}