iOS学习笔记（3）－－初识UINavigationController（无storyboard）

纯代码创建导航控制器UINavigationController

在Xcode6.1中创建single view application的项目，删除Main.storyboard文件，删除info.plist中main storyboard相关属性，依靠代码编写UI视图，研究导航控制器栈的原理。

AppDelegate.h文件代码

 #import <UIKit/UIKit.h>
 
 @interface AppDelegate : UIResponder <UIApplicationDelegate>
 
 @property (strong, nonatomic) UIWindow *window;
 
 @end

AppDelegate.m

 #import "AppDelegate.h"
 #import "ViewController.h"
 @interface AppDelegate ()
 
 @end
 
 @implementation AppDelegate
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
     // Override point for customization after application launch.
     self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
     ViewController *firstView = [[ViewController alloc] init];
     UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:firstView];
     [nav.navigationController pushViewController:firstView animated:YES];
     self.window.rootViewController = nav;
     self.window.backgroundColor = [UIColor whiteColor];
     [self.window makeKeyAndVisible];
 
     return YES;
 }
 
 - (void)applicationWillResignActive:(UIApplication *)application {
     // 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.
     // 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.
 }
 
 - (void)applicationDidEnterBackground:(UIApplication *)application {
     // 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.
     // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
 }
 
 - (void)applicationWillEnterForeground:(UIApplication *)application {
     // 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.
 }
 
 - (void)applicationDidBecomeActive:(UIApplication *)application {
     // 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.
 }
 
 - (void)applicationWillTerminate:(UIApplication *)application {
     // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
 }
 
 @end

• 若要实现导航控制器对视图的切换导航，UINavigationController就必须成为视图的根控制器
• 导航控制器中存在导航控制栈，显示新视图的过程就是入栈的过称[nav.navigationController pushViewController:firstView animated:YES]
• 出栈则为pop

ViewController.h

 #import <UIKit/UIKit.h>
 
 @interface ViewController : UIViewController
 
 - (IBAction)goToSecondView:(id)sender;
 @end

第二个视图的控制器头文件，定义IBAction方法，用来显示第二个视图

ViewController.m

 #import "ViewController.h"
 #import "SecondViewController.h"
 
 @interface ViewController ()
 
 @end
 
 @implementation ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view, typically from a nib.
     UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
     label.text = @"This the first view";
     [self.view addSubview:label];
     UIButton *nextView = [[UIButton alloc] initWithFrame:CGRectMake(, , , )];
     [nextView setTitle:@"Next View" forState:UIControlStateNormal];
     [nextView setBackgroundColor:[UIColor blueColor]];
     [nextView setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
     [nextView addTarget:self action:@selector(goToSecondView:) forControlEvents:UIControlEventTouchDown];
     [self.view addSubview:nextView];
 
 }
 
 - (IBAction)goToSecondView:(id)sender {
     SecondViewController *second = [[SecondViewController alloc] init];
     [self.navigationController pushViewController:second animated:YES];
 //    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"123" message:@"321" delegate:nil cancelButtonTitle:@"111" otherButtonTitles: nil];
 //    [alert show];
     NSLog(@"click");
 }
 
 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }
 
 @end

• 代码创建UILabel的方法是[[UILabel alloc] initWithFrame:CGRectMake(10, 50, 200, 40)]
• 将UI视图添加到当前控制器的视图中的方法[self.view addSubview:label]
• 创建UIButton并设置按钮的背景颜色、标题等属性
• 将视图与IBAction方法关联的代码[nextView addTarget:self action:@selector(goToSecondView:) forControlEvents:UIControlEventTouchDown]
• 创建第二视图控制器的实例，并把视图控制器压入控制器栈即可显示新视图[self.navigationController pushViewController:second animated:YES];

SecondViewController.h

 #import <UIKit/UIKit.h>
 
 @interface SecondViewController : UIViewController
 - (IBAction)goToThird:(id)sender;
 @end

 #import "SecondViewController.h"
 #import "ThirdViewController.h"
 
 @interface SecondViewController ()
 
 @end
 
 @implementation SecondViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view.
     UIButton *nextView = [[UIButton alloc] initWithFrame:CGRectMake(, , , )];
     [nextView setTitle:@"Next View" forState:UIControlStateNormal];
     [nextView setBackgroundColor:[UIColor blueColor]];
     [nextView setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
     [nextView addTarget:self action:@selector(goToThird:) forControlEvents:UIControlEventTouchDown];
     [self.view addSubview:nextView];
 }
 
 - (void)viewDidAppear:(BOOL)animated {
     UILabel *secondLabel = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
     secondLabel.text = @"This is the second view";
     [self.view addSubview:secondLabel];
 }
 
 - (IBAction)goToThird:(id)sender {
     ThirdViewController *third = [[ThirdViewController alloc] init];
     [self.navigationController pushViewController:third 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

ThirdViewController.h

 #import <UIKit/UIKit.h>
 
 @interface ThirdViewController : UIViewController
 
 @end

ThirdViewController.m

 #import "ThirdViewController.h"
 
 @interface ThirdViewController ()
 
 @end
 
 @implementation ThirdViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view.
 }
 
 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }
 
 - (void)viewDidAppear:(BOOL)animated {
     UILabel *secondLabel = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
     secondLabel.text = @"This is the third view";
     [self.view addSubview:secondLabel];
 }
 
 /*
 #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

第二视图和第三视图代码结构与第一视图类似，输入完以上代码后，运行程序即可实现简单的导航控制器切换视图的功能。