我想在后台应用程序中取消Http连接。这是我的代码:overridefuncviewDidLoad(){super.viewDidLoad()leturl=URL(string:"myurl")lettask=URLSession.shared.dataTask(with:url!){data,response,erroringuarderror==nilelse{print(error)return}guardletdata=dataelse{print("Dataisempty")return}do{ifletjsonResult=tryJSONSerialization.json