UINavigationControl

// UINavigationController 以栈的形式 管理 各个Controller 显示的是位于栈顶的Controller
// 推出也是后入栈的先推出

// 1. 在AppDelegate.m中,初始化rootViewController
    RootViewController *rootVC = [[RootViewController alloc]init];
    // 初始化navigationController
    UINavigationController *rootNC = [[UINavigationController alloc]initWithRootViewController:rootVC];
    // self.window 的主 controller 设置成 rootNC
    self.window.rootViewController = rootNC;
// 2. 界面交换方法
   // 进入下一个controller
    FirstViewController *firstVC = [[FirstViewController alloc]init];
    [self.navigationController pushViewController:firstVC animated:YES];


    // 推出当前 controller 回到上一个 controller
    //[self.navigationController popViewControllerAnimated:YES];
    //2. 回到根视图
    //[self.navigationController popToRootViewControllerAnimated:YES];
    //3. 可以拿到 navigationController 下面管理的UIViewControllers
    NSArray *temp = self.navigationController.viewControllers;
    [self.navigationController popToViewController:temp[1] animated:YES];

UINavigationBar

    // navigationItem
    // 1.设置标题
    self.navigationItem.title = @"rootView";
    // 标题还可以设置一个view,view里面可以设置imageView,button之类的
    //self.navigationItem.titleView =

  // 2.设置左button
    //可以用图片初始化
    //self.navigationItem.leftBarButtonItem = [UIBarButtonItem alloc]initWithImage:<#(UIImage *)#> style:<#(UIBarButtonItemStyle)#> target:<#(id)#> action:<#(SEL)#>
    // 可以用文字初始化
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"呵呵" style:UIBarButtonItemStylePlain target:self action:@selector(leftBarButtonAction:)];

    // 3.设置右button
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"firstView" style:UIBarButtonItemStyleDone target:self action:@selector(rightBarButtonAction:)];

    //4.设置barbutton 的背景颜色
    self.navigationController.navigationBar.barTintColor = [UIColor orangeColor];
    // 设置背景图
    // self.navigationController.navigationBar setBackgroundImage:<#(UIImage *)#> forBarMetrics:<#(UIBarMetrics)#>
    // 5.设置做按钮和右按钮的字体颜色
    self.navigationController.navigationBar.tintColor = [UIColor redColor];
    //  6.可以把自带的backButton(返回按钮)隐藏
    self.navigationItem.hidesBackButton = YES;

界面间传值

正向传值(属性传值)

@interface FirstViewController : UIViewController
// 1. 正向传值可以通过属性,,但是属性必须写在本类的.h文件中 不能写在延展里面
@property(nonatomic,retain)NSString *passStr;
@end

#import "FirstViewController.h"
@interface FirstViewController ()
@property(nonatomic,retain)UILabel *showLabel;
@end

@implementation FirstViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor greenColor];
    self.showLabel = [[UILabel alloc]initWithFrame:CGRectMake(50, 200, 200, 50)];
    self.showLabel.backgroundColor = [UIColor grayColor];
    // 2. 接受上一个页面传递过来的String 
    self.showLabel.text = self.passStr;
    [self.view addSubview:self.showLabel];
   
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"rootView" style:UIBarButtonItemStyleDone target:self action:@selector(firstViewAction:)];
    self.navigationItem.title = @"firstView";
}
-(void)firstViewAction:(UIBarButtonItem *)sender{
    [self.navigationController popViewControllerAnimated:YES];
}

#import "RootViewController.h"
#import "FirstViewController.h”
@interface RootViewController ()<UITextFieldDelegate>
@property(nonatomic,retain)UITextField *textField;
@end

@implementation RootViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor orangeColor];
    self.textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 100, 200, 50)];
    self.textField.backgroundColor = [UIColor grayColor];
    [self.view addSubview: self.textField]; 
    self.textField.delegate = self;
   
    self.navigationItem.title = @"rootView";
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"firstView" style:UIBarButtonItemStyleDone target:self action:@selector(rootViewAction:)];
}
- (void)rootViewAction:(UIBarButtonItem *)sender{
    FirstViewController *firstView = [[FirstViewController alloc]init];
    [self.navigationController pushViewController:firstView animated:YES];
    // 3. 将textField中 的文本,赋值给下一个controller的属性
    firstView.passStr = self.textField.text;
}

2.反向传值(代理传值)

// 1. 写协议
@protocol PassValueDelegate <NSObject>
- (void)passValue:(NSString *)aString;
@end
// 2. 在.h中 声明一个代理的属性
@interface FirstViewController : UIViewController
@property(nonatomic,assign)id<PassValueDelegate>delegate;
@end
// 3. 在.m中 让代理先执行协议里的方法
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"rootView" style:UIBarButtonItemStyleDone target:self action:@selector(firstViewAction:)];

- (void)firstViewAction:(UIBarButtonItem *)sender{
    [self.delegate passValue:self.textField.text];
    [self.navigationController popViewControllerAnimated:YES];
}
// 4. 找一个Controller遵循协议
@interface RootViewController ()<PassValueDelegate>
// 5. 设置当前Controller为代理
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"firstView" style:UIBarButtonItemStyleDone target:self action:@selector(RootViewAction:)];

- (void)RootViewAction:(UIBarButtonItem *)sender{
    FirstViewController *firstVIew = [[FirstViewController alloc]init];
    // 设置代理
    firstVIew.delegate = self;
    [self.navigationController pushViewController:firstVIew animated:YES];
}
// 6. 让Controller执行协议里的方法
- (void)passValue:(NSString *)aString{
    self.label.text = aString;
}