导航器-页面加载

右移时，负数补1，正数补0，补符号位；
左移补0；
移位可以用来取数。
位操作时最好不要用（+—*/）
  
shell
  gg=G对齐
  command d退出程序


作用域：
 在复合语句里定义的变量只能在复合语句中使用

// 在.m文件中定义的属性、成员变量、以及方法，只能在当前类中访问，不开放出去
// 面向对象程序设计的原则：开放封闭原则，开闭原则，对内部开放，对外部封闭



#import "AppDelegate.h"
#import "FisrtViewController.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];
    
    //声明一个视图控制器用于导航器加载
    FisrtViewController *fViewController=[[FisrtViewController alloc]init];
    fViewController.view.backgroundColor=[UIColor blueColor];
    //定义一个导航器来加载第一个视图控制器，即跟视图控制器
    UINavigationController *navController=[[UINavigationController alloc]initWithRootViewController:fViewController];
    self.window.rootViewController=navController;
    
    return YES;
}

//第一个视图控制器类的实现文件
#import "FisrtViewController.h"
#import "SecondViewController.h"
@interface FisrtViewController ()

@end

@implementation FisrtViewController

- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    //在跟视图控制器中添加一个标签和按钮
    UILabel *label=[[UILabel alloc]initWithFrame:CGRectMake(0, 64, 100, 30)];
    label.text=@"我是label";
    label.textColor=[UIColor redColor];
    label.backgroundColor=[UIColor whiteColor];
    [self.view addSubview:label];
    
    UIButton *nextBtn=[UIButton buttonWithType:UIButtonTypeCustom];
    nextBtn.frame=CGRectMake(220, 64, 100, 30);
    [nextBtn setTitle:@"nextView" forState:UIControlStateNormal];
    [nextBtn setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
    nextBtn.backgroundColor=[UIColor redColor];
    [nextBtn addTarget:self action:@selector(nextDidClik:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:nextBtn];
    
    UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(30, 144, 240, 296)];
    imageView.image=[UIImage imageNamed:@"1.png"];
    [self.view addSubview:imageView];
}
//按钮触发时加载到第二个视图控制器
- (void)nextDidClik:(UIButton *)sender
{
    SecondViewController *secondViewController=[[SecondViewController alloc]init];
    secondViewController.view.backgroundColor=[UIColor yellowColor];
    
    [self.navigationController pushViewController:secondViewController animated:YES];
    
}



//第二个视图控制器类的实现文件
#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    UIButton *beforeBtn=[UIButton buttonWithType:UIButtonTypeCustom];
    beforeBtn.frame=CGRectMake(0, 64, 100, 30);
    [beforeBtn setTitle:@"beforeView" forState:UIControlStateNormal];
    [beforeBtn setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
    beforeBtn.backgroundColor=[UIColor redColor];
    [beforeBtn addTarget:self action:@selector(beforeBtn:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:beforeBtn];

    
}
//按钮触发时返回到前一个视图控制器中
- (void)beforeBtn:(UIButton *)sender
{
    [self.navigationController popToRootViewControllerAnimated:YES];
}