AppDelegate.m

#import "AppDelegate.h"
#import "RootViewController.h"

@interface AppDelegate ()
@end
@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    
    self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    
    RootViewController *rootViewController = [[RootViewController alloc] init];
    rootViewController.title = @"首页";
    return YES;
}

RootViewController.m

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.navigationController.navigationBar.translucent = NO;
    //改变navigationBar颜色
    self.navigationController.navigationBar.barTintColor = [UIColor orangeColor];
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = CGRectMake(100, 100, 50, 30);
    button.backgroundColor = [UIColor  orangeColor];
    [button setTitle:@"push" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
  }
-(void)buttonAction:(UIButton *)button{
    SecondViewController *secondViewController = [[SecondViewController alloc] init];
    //self.navigationController.navigationBarHidden = YES;

    [self.navigationController pushViewController:secondViewController animated:YES];

}

SecondViewController.m

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    self.view.backgroundColor = [UIColor redColor];
    
    
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"<" style:UIBarButtonItemStylePlain target:self action:@selector(buttomAction:)];
    
    UIButton *button1 = [UIButton buttonWithType:UIButtonTypeCustom];
    button1.frame = CGRectMake(100, 200, 50, 30);
    button1.backgroundColor = [UIColor greenColor];
    [button1 setTitle:@"回来" forState:UIControlStateNormal];
    [button1 addTarget:self action:@selector(buttomAction:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button1];
   }
-(void)buttomAction:(NSString *)button{

    [self.navigationController popViewControllerAnimated:YES];
    self.navigationController.navigationBarHidden = NO;
    
    
}