import "AppDelegate.h"

import "RootViewController.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

• (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
  // Override point for customization after application launch.
  self.window.backgroundColor = [UIColor whiteColor];
  [self.window makeKeyAndVisible];

  // 初始化RootVC（rootVC为navC的根视图控制器，也就是首个被navC管理的视图控制器）
  RootViewController *rootVC = [[RootViewController alloc]init];
  // 初始化navC (初始化方法使用的是可以给navC设置根视图控制器)
  UINavigationController *navC = [[UINavigationController alloc]initWithRootViewController:rootVC];

  // 设置navigationBar的tintColor（前端渲染的颜色） 其实是navigationBar上面返回按钮的颜色
  navC.navigationBar.tintColor = [UIColor redColor];
  // 改变navigationBar的背景颜色
  // navC.navigationBar.backgroundColor = [UIColor yellowColor];
  // 改变navigationBar的透明状态（默认为半透明）
  navC.navigationBar.translucent = NO;
  // 设置背景图片
  // UIBarMetricsDefault 横、竖屏状态下的背景图片
  // UIBarMetricsCompact 横屏状态下的背景图片
  [navC.navigationBar setBackgroundImage:[UIImage imageNamed:@"1.png"] forBarMetrics:UIBarMetricsCompact];
  // 设置navigationBar的样式 (系统提供的只有两种，浅白色和黑色)
  navC.navigationBar.barStyle = UIBarStyleBlack;

  // 为window设置根视图控制器
  [self.window setRootViewController:navC];

  return YES;
  }

---

import "RootViewController.h"

import "SecondViewController.h"

@interface RootViewController ()

@end

@implementation RootViewController

// 视图将要出现的时候
-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
NSLog(@"Root___%@",self.navigationController.viewControllers);
}

• (void)viewDidLoad {
  [super viewDidLoad];

  // 设置导航栏标题
  self.navigationItem.title = @"根视图控制器";
  // 设置titleView（标题视图）
  UILabel *titleLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 300, 44)];
  titleLabel.text = @"titleView";
  titleLabel.backgroundColor = [UIColor greenColor];
  titleLabel.textAlignment = NSTextAlignmentCenter;
  self.navigationItem.titleView = titleLabel;
  // 为了下个界面的返回按钮处没有文字，在已经使用titleView的情况下，可以将标题设置为空字符串
  self.navigationItem.title = @"";
  // 设置navigationBar的右按钮
  // <#(UIBarButtonSystemItem)#>:当前按钮的系统样式

  UIBarButtonItem *rightBtnItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(rightBarBtnAction:)];
  // 设置右侧按钮
  self.navigationItem.rightBarButtonItem = rightBtnItem;

  UIButton *pushBtn = [UIButton buttonWithType:UIButtonTypeSystem];
  [pushBtn setTitle:@"push" forState:UIControlStateNormal];
  pushBtn.frame = CGRectMake(100, 100, 100, 100);
  [pushBtn addTarget:self action:@selector(pushAction:) forControlEvents:UIControlEventTouchUpInside];
  [self.view addSubview:pushBtn];
  }

// 导航栏右侧按钮回调方法
-(void)rightBarBtnAction:(UIBarButtonItem*)sender{
// push到下个界面
SecondViewController *secondVC = [[SecondViewController alloc]init];
[self.navigationController pushViewController:secondVC animated:YES];
}

// 按钮的回调方法，进入下一个界面
-(void)pushAction:(UIButton*)sender{
// 打印viewController，看一下当前被navC所管理的视图控制器们
NSArray *viewCs = self.navigationController.viewControllers;
NSLog(@"%@",viewCs);
// 进入到下一个界面（为导航控制器新添加一个要被管理的视图控制器）
SecondViewController *secondVC = [[SecondViewController alloc]init];

//  推送到下一个界面
/**
 *   pushViewController:将要显示的视图控制器
     animated:切换中是否需要动画
     push的操作，就是将所要被管理的视图控制器入栈，实际执行的动作就是：[self.navigationController.viewControllers addObjects:secondVC]在此处secondVC就会位于栈顶
     viewControllers：该属性的返回类型为NSArray，但是我们一定得记得，viewControllers实际的类型是NSMutableArray。这里体现了面向对象多态的特性
 */
[self.navigationController pushViewController:secondVC animated:YES];
NSLog(@"push*****%@",self.navigationController.viewControllers);

//  得到当前位于栈顶的视图控制器  viewControllers这个数组的最后一个元素，一般都在栈顶
NSLog(@"top____%@",self.navigationController.topViewController);

//  得到当前正在显示的视图控制器
NSLog(@"visible~~~~~~%@",self.navigationController.visibleViewController);

}

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

---

import "SecondViewController.h"

import "ThirdViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

• (void)viewDidLoad {
  [super viewDidLoad];

  // 设置左边按钮
  UIBarButtonItem *leftBtnItem = [[UIBarButtonItem alloc]initWithTitle:@"Back" style:UIBarButtonItemStyleDone target:self action:@selector(leftBackBtnAction:)];
  self.navigationItem.leftBarButtonItem = leftBtnItem;

  UIButton *leftBtn = [UIButton buttonWithType:UIButtonTypeSystem];
  leftBtn.frame = CGRectMake(0, 0, 50, 50);
  [leftBtn setTitle:@"button" forState:UIControlStateNormal];
  // 当我们使用自定义视图（UIView及其子类）作为导航条按钮的时候，需要使用此初始化方法
  UIBarButtonItem *barItem = [[UIBarButtonItem alloc]initWithCustomView:leftBtn];

  // 定义一组左侧按钮
  self.navigationItem.leftBarButtonItems = @[barItem,leftBtnItem];

  UIButton *backBtn = [UIButton buttonWithType:UIButtonTypeSystem];
  [backBtn setFrame:CGRectMake(100, 100, 100, 100)];
  [backBtn setTitle:@"popBtn"
  forState:UIControlStateNormal];
  [backBtn addTarget:self
  action:@selector(popAction:)
  forControlEvents:UIControlEventTouchUpInside];
  [self.view addSubview:backBtn];

UIButton *thirdBtn = [UIButton buttonWithType:UIButtonTypeSystem];
[thirdBtn setFrame:CGRectMake(100, 200, 100, 100)];
[thirdBtn setTitle:@"thirdBtn"
         forState:UIControlStateNormal];
[thirdBtn addTarget:self
            action:@selector(thirdAction:)
  forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:thirdBtn];

}

// 左边按钮的回调方法
-(void)leftBackBtnAction:(UIBarButtonItem*)sender{
[self.navigationController popToRootViewControllerAnimated:YES];
}

// 返回上级界面（出栈）
-(void)popAction:(UIButton*)sender{
// 出栈 实际所进行的操作是：[self.navigationController.viewControllers removeObject:self]
// 更准确的写法：[self.navigationController.viewControllers removeObject:self.navigationController.viewControllers.lastObject]
// 在出栈之前打印当前navC过管理的视图控制器
NSLog(@"pre ***%@",self.navigationController.viewControllers);
// [self.navigationController popViewControllerAnimated:YES];
// 返回到指定视图控制器
[self.navigationController popToViewController:self.navigationController.viewControllers.firstObject animated:YES];
// 出栈之后，再次打印当前navC所管理的视图控制器
NSLog(@"pop ~~~%@",self.navigationController.viewControllers);

}

// 跳转到thirdVC
-(void)thirdAction:(UIButton*)sender{

ThirdViewController *thirdVC = [[ThirdViewController alloc]init];
[self.navigationController pushViewController:thirdVC animated:YES];

}

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

/*

pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation

• (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
  // Get the new view controller using [segue destinationViewController].
  // Pass the selected object to the new view controller.
  }
  */

@end

import "ThirdViewController.h"

@interface ThirdViewController ()

@end

@implementation ThirdViewController

• (void)viewDidLoad {
  [super viewDidLoad];

  UIButton *thirdBackBtn = [UIButton buttonWithType:UIButtonTypeSystem];
  [thirdBackBtn setFrame:CGRectMake(100, 200, 200, 100)];
  [thirdBackBtn setTitle:@"thirdBackRootBtn"
  forState:UIControlStateNormal];
  [thirdBackBtn addTarget:self
  action:@selector(thirdBackRootAction:)
  forControlEvents:UIControlEventTouchUpInside];
  [self.view addSubview:thirdBackBtn];

}

-(void)thirdBackRootAction:(UIButton*)sender{
// 返回根视图控制器
NSLog(@"third___%@",self.navigationController.viewControllers);
[self.navigationController popToRootViewControllerAnimated:YES];
NSLog(@"thirdPop___%@",self.navigationController.viewControllers);

}

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

/*

pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation

• (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
  // Get the new view controller using [segue destinationViewController].
  // Pass the selected object to the new view controller.
  }
  */

@end