隐藏或删除顶部的导航条

代码成功运行，但是在页面顶部多出来一个导航条，我想隐藏起来或者删除。

ClsMainPageAppDelegate.m

#import "ClsMainPageAppDelegate.h"
#import "ClsTermsandConditionViewController.h"
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
    ClsTermsandConditionViewController *ivc = [storyboard instantiateViewControllerWithIdentifier:@"termsandConditionControl"];
    UINavigationController *navigationController=[[UINavigationController alloc] initWithRootViewController:ivc];
    self.window.rootViewController=nil;
    self.window.rootViewController = navigationController;
    [self.window makeKeyAndVisible];
}

读一下文件说明： UINavigationController Class Reference

[navigationController setNavigationBarHidden:YES];

在ClsTermsandConditionViewController.m文件的viewWillAppear 或 viewDidLoad中加入如下代码

-(void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self.navigationController setNavigationBarHidden:YES];
}