网上很多人写的都很烦,要么太理论,要么不好实现.写个demo帮助理解

//AppDelegate.m

- (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];
    
    RootViewController *rootView=[[RootViewController alloc]init];
    
    UINavigationController *nav = [[UINavigationController alloc]initWithRootViewController:rootView];
    
    [_window setRootViewController:nav];
    
   
    
    return YES;
}

我的RootView.ViewController

//
//  ViewController.m
//  First
//
//  Created by zcw on 2017/12/6.
//  Copyright © 2017年 zcw. All rights reserved.
//

#import "ViewController.h"
#import "SecondViewController.h"
@interface ViewController ()
{
    double length;   // Length of a box
    double breadth;  // Breadth of a box
    double height;   // Height of a box
}
@end

@implementation ViewController
@synthesize mystr = _myStr;
- (void)viewDidLoad {
    [super viewDidLoad];
    
    
    
    //Nav
    [self.navigationController.navigationBar setTranslucent:NO];//设置navigationbar的半透明

    self.title = @"RootViewController";//设置navigationbar上显示的标题

    [self.navigationController.navigationBar setBarTintColor:[UIColor purpleColor]];//设置navigationbar的颜色

    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonItemStyleDone target:self action:Nil];//设置navigationbar左边按钮

    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonItemStylePlain target:self action:Nil];//设置navigationbar右边按钮

    [self.navigationController.navigationBar setTintColor:[UIColor whiteColor]];//设置navigationbar上左右按钮字体颜色
    
//    self.navigationItem.rightBarButtonItem setTarget:<#(id)#>
//    动态添加一个按钮
    
    
    
    // Do any additional setup after loading the view, typically from a nib.
    UIButton * button = [[UIButton alloc] init];
    
    [button setTitle:@"点击我跳转" forState:UIControlStateNormal];
    [button setTitle:@"摸我干啥" forState:UIControlStateHighlighted];
    
    [button setTitleColor:[UIColor yellowColor] forState:UIControlStateNormal];
    [button setTitleColor:[UIColor greenColor] forState:UIControlStateHighlighted];
    
    UIImage *imgNormal = [UIImage imageNamed:@"btn_01"];
    UIImage *imgHighted = [UIImage imageNamed:@"btn_02"];
    
    [button setBackgroundImage:imgNormal forState:(UIControlStateNormal)];
    [button setBackgroundImage:imgHighted forState:(UIControlStateHighlighted)];
    button.frame = CGRectMake(50, 50, 299, 126);
    [button addTarget:self action:@selector(buttonPrint) forControlEvents:(UIControlEventTouchUpInside)];
    
    [self.view addSubview:button];
    
    
    
    
}

- (void)buttonPrint
{
    printf("测试打印");
    SecondViewController *nextVc = [[SecondViewController alloc]init];
//    [self presentViewController:nextVc animated:YES completion:nil];
    
    [self.navigationController pushViewController:nextVc animated:YES];
    


   
    

  
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.

}


@end

SecondVIewController

//
//  SecondViewController.m
//  First
//
//  Created by zcw on 2017/12/6.
//  Copyright © 2017年 zcw. All rights reserved.
//

#import "SecondViewController.h"
#import "ViewController.h"
@interface SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    UILabel *label = [[UILabel alloc] init];
    label.text = @"second page";
    [label setTextColor:[UIColor yellowColor]];
    label.frame = CGRectMake(200, 200, 50, 200);
    
    
    
    UIButton * button = [[UIButton alloc] init];
    
    [button setTitle:@"-----点击我跳转" forState:UIControlStateNormal];
    [button setTitle:@"-----摸我干啥" forState:UIControlStateHighlighted];
    
    [button setTitleColor:[UIColor yellowColor] forState:UIControlStateNormal];
    [button setTitleColor:[UIColor greenColor] forState:UIControlStateHighlighted];
    
    UIImage *imgNormal = [UIImage imageNamed:@"btn_01"];
    UIImage *imgHighted = [UIImage imageNamed:@"btn_02"];
    
    [button setBackgroundImage:imgNormal forState:(UIControlStateNormal)];
    [button setBackgroundImage:imgHighted forState:(UIControlStateHighlighted)];
    button.frame = CGRectMake(50, 50, 299, 126);
    [button addTarget:self action:@selector(buttonPrint) forControlEvents:(UIControlEventTouchUpInside)];
    
    [self.view addSubview:button];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)buttonPrint
{
    printf("测试打印2222");
//    [self dismissViewControllerAnimated:true completion:nil];
    [self.navigationController popToRootViewControllerAnimated:YES];//回到根视图界面
}


@end