iOS 更改导航子控制器

实现push下一页+pop当前页的效果

    NSArray *vcs = self.navigationController.viewControllers;
    NSMutableArray *newVCS = [NSMutableArray array];
    if ([vcs count] > 0) {
        for (int i=0; i < [vcs count]-1; i++) {
            [newVCS addObject:[vcs objectAtIndex:i]];
        }
    }
    [newVCS addObject:vc];
    [self.navigationController setViewControllers:newVCS animated:NO];