MBProgressHud视图自定义在Swift 3中不起作用并且不显示吗？

我正在使用以下代码，但没有显示进度平视显示器，所以请为此提供帮助。

let loadingHUD = MBProgressHUD() 

loadingHUD.mode = MBProgressHUDModeCustomView
loadingHUD.labelText = nil
loadingHUD.detailsLabelText = nil
let customView = UIView.init(frame: CGRect(x: 0, y: 0, width: 80, height: 80))

let gifmanager = SwiftyGifManager(memoryLimit:20)
let gif = UIImage(gifName: "miniballs1.gif")
let imageview = UIImageView(gifImage: gif, manager: gifmanager)
imageview.frame = CGRect(x: 0 , y: 0, width: customView.frame.width, height: customView.frame.height)
customView.addSubview(imageview)
customView.bringSubview(toFront: imageview)

loadingHUD.customView = customView
loadingHUD.customView.bringSubview(toFront: customView)
loadingHUD.show(true)