在UIAlertController弹窗后,使用popToViewController返回上级页面,报错
popToViewController:transition: called on <UINavigationController 0x7fc27b8ac000> while an existing transition or presentation is occurring; the navigation stack will not be updated.
原因是当UIAlertController在执行的时候,不能进行堆栈的操作,navigation的堆栈更新不成功,所以页面不能跳转