返回到指定页面

NSMutableArray *vcArr = [NSMutableArray arrayWithArray:self.navigationController.viewControllers];

           if (![vcArr[vcArr.count-2] isKindOfClass:NSClassFromString(@"KeyViewController")])

           {

               [vcArr insertObject:[[NSClassFromString(@"KeyViewController") alloc]init] atIndex:vcArr.count-1];

           }

           self.navigationController.viewControllers=[vcArr copy];

           [self popToViewControllerClass:NSClassFromString(@"KeyViewController") animated:YES];