swift pop 到指定的控制器

for i in 0..<(self.navigationController?.viewControllers.count)! {
if self.navigationController?.viewControllers[i].isKindOfClass(LoanViewController) == true{
// send notification
// NSNotificationCenter.defaultCenter().postNotificationName("RefreshData", object: nil)


_ = self.navigationController?.popToViewController(self.navigationController?.viewControllers[i] as! LoanViewController, animated: true)
break
}

}