overridefuncprepareForSegue(segue:UIStoryboardSegue,sender:AnyObject?){ifsegue.identifier=="toChat2"{guardletnavController=segue.destinationViewControlleras?UINavigationController,letchatController=navController.viewControllers.firstas?ChatViewControllerelse{return}letindexPaths=self.tableView!.

letchatController=ChatLogController()chatController.user=userletnav:UINavigationController=UINavigationController(rootViewController:chatController)self.presentViewController(nav,animated:true,completion:nil)上面的代码有效，我试图在呈现之前将用户传递给下一个ViewController但是，这不起作用，它在下一个ViewController中为用户提供了nil:letchatCon