1 #import "AppDelegate.h"
 2 #import "ViewController.h"
 3 
 4 @interface AppDelegate ()
 5 
 6 @end
 7 
 8 @implementation AppDelegate
 9 
10 
11 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
12     //创建window
13     self.window = [[UIWindow alloc]init];
14     
15     //设置window的大小
16     CGSize screenSize = [[UIScreen mainScreen]bounds].size;
17     self.window.frame = CGRectMake(0, 0, screenSize.width, screenSize.height);
18     
19     //为window设置根控制器
20     ViewController *VC = [[ViewController alloc]init];
21     UINavigationController *naVC = [[UINavigationController alloc]initWithRootViewController:VC];
22     
23     self.window.rootViewController = naVC;
24     
25     //接收用户输入并显示
26     [self.window makeKeyAndVisible];
27     
28     return YES;
29 }
30 
31 - (void)applicationWillResignActive:(UIApplication *)application {
32     // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
33     // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
34 }
35 
36 - (void)applicationDidEnterBackground:(UIApplication *)application {
37     // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
38     // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
39 }
40 
41 - (void)applicationWillEnterForeground:(UIApplication *)application {
42     // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
43 }
44 
45 - (void)applicationDidBecomeActive:(UIApplication *)application {
46     // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
47 }
48 
49 - (void)applicationWillTerminate:(UIApplication *)application {
50     // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
51 }
52 
53 @end

 1 #import "ViewController.h"
 2 #import "secondViewController.h"
 3 
 4 @interface ViewController ()
 5 
 6 @end
 7 
 8 @implementation ViewController
 9 
10 - (void)viewDidLoad {
11     [super viewDidLoad];
12     [self.view setBackgroundColor:[UIColor yellowColor]];
13     
14     //设置导航栏
15     //设置标题
16     self.navigationItem.title = @"First";
17     
18     //设置返回按钮
19     self.navigationItem.backBarButtonItem.title = @"first";
20     
21     //设置右边的按钮
22     self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addClicked:)];
23 }
24 
25 -(void)addClicked:(UIBarButtonItem*)sender
26 {
27     secondViewController *secondVC = [[secondViewController alloc]init];
28     
29     //将新的控制器压入导航控制器
30     [self.navigationController pushViewController:secondVC animated:YES];
31 }
32 
33 @end

 1 #import "secondViewController.h"
 2 
 3 @interface secondViewController ()
 4 
 5 @end
 6 
 7 @implementation secondViewController
 8 
 9 - (void)viewDidLoad {
10     [super viewDidLoad];
11     self.view.backgroundColor = [UIColor redColor];
12     
13     //设置导航栏
14     //1、设置标题
15     self.navigationItem.title = @"Second";
16     
17     //2.设置左边的按钮
18     self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"Return" style:UIBarButtonItemStylePlain target:self action:@selector(backClicked:)];
19 }
20 
21 -(void)backClicked:(UIBarButtonItem*)sender
22 {
23     //将当前的控制器弹出导航控制器
24     [self.navigationController popToRootViewControllerAnimated:YES];
25 }
26 @end