为什么我的gif在Swift游乐场没有动画效果？

import UIKit
import PlaygroundSupport

// 创建UIImageView实例
let imageView = UIImageView()

// 加载gif文件
if let gifURL = Bundle.main.url(forResource: "your_gif_file", withExtension: "gif"),
   let gifData = try? Data(contentsOf: gifURL),
   let gifImage = UIImage.gifImageWithData(gifData) {
    // 将gif图像分配给UIImageView
    imageView.image = gifImage
}

// 设置UIImageView的位置和大小
imageView.frame = CGRect(x: 0, y: 0, width: 200, height: 200)

// 将UIImageView添加到Playground的视图层次结构中
PlaygroundPage.current.liveView = imageView