显示UIActivityIndi​​cator持续x秒

import UIKit

class ViewController: UIViewController {
    let activityIndicatorView = UIActivityIndicatorView(style: .gray)

    override func viewDidLoad() {
        super.viewDidLoad()

        // 设置UIActivityIndicatorView的位置
        activityIndicatorView.center = view.center

        // 将UIActivityIndicatorView添加到视图层次结构中
        view.addSubview(activityIndicatorView)

        // 开始动画
        activityIndicatorView.startAnimating()

        // 停止动画
        Timer.scheduledTimer(timeInterval: 5, target: self, selector: #selector(stopActivityIndicator), userInfo: nil, repeats: false)
    }

    @objc func stopActivityIndicator() {
        activityIndicatorView.stopAnimating()
    }
}