带导航的控制器上面再加个带导航的控制器，但第二个导航只从屏幕左边隔一定距离显示到右边的框

FilterViewController *filter = [[FilterViewController
alloc]init];

        UINavigationController *nav = [[UINavigationController
alloc]initWithRootViewController:filter];

        [nav.view
setFrame:CGRectMake((40/375.0)
* WIDTH, 0,
WIDTH - (40/375.0) *
WIDTH, HEIGHT)];

        [self.navigationController
addChildViewController:nav];

        [self.navigationController.view
addSubview:nav.view];

在点击第二个导航的返回按钮时要

 [self.navigationController.view
removeFromSuperview];

    [self.navigationController
removeFromParentViewController];

点击第一个控制器的空白时要记得

for (UIView *vv
in self.navigationController.childViewControllers)
{

        NSLog(@"%@",vv.class);

        if ([vv
isKindOfClass:[UINavigationController
class]]) {

            UINavigationController *na = (UINavigationController *)vv;

            [na removeFromParentViewController];

            [na.view
removeFromSuperview];

        }

    }