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iPhone开发之NavigationController

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作者 正文
   发表时间:2012-03-23  


在上图中红线框住的就是导航栏,应用也很广泛,系统自带应用也在用它。如何从零创建一个导航栏应用。
新建项目,可以选择“Master-Detail Application”,但是默认就创建了TableView视图,这个我们不需要,所以还是从空项目创建,选择“Empty Appliction”,项目命名为“NavigationDemo”
新建一个视图,“New file..” -> “UIViewController subclass”,命名为RootViewController,并勾选“With XIB for user interface”
修改AppDelegate.h和AppDelegate.m源代码
//  AppDelegate.h
 
#import <UIKit/UIKit.h>
 
@interface AppDelegate : UIResponder <UIApplicationDelegate>
{
    UINavigationController *navController;
}
 
@property (strong, nonatomic) UIWindow *window;
 
@end

//  AppDelegate.m
 
#import "AppDelegate.h"
#import "RootViewController.h"
 
@implementation AppDelegate
 
@synthesize window = _window;
 
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    navController = [[UINavigationController alloc] init];
    RootViewController *rootViewController = [[RootViewController alloc] init];
 
 
    // 这时navController会增加rootViewController的引用计数
    [navController pushViewController:rootViewController animated:NO];
    [self.window addSubview:navController.view];
    [self.window makeKeyAndVisible];
	// 所以这里可以release先前的引用,UINavigationController它会掌控rootViewController
	[rootViewController release];
    return YES;
}
 
...
 
- (void)dealloc
{
    [navController release];
    [self.window release];
    [super dealloc];
}
 
@end


这时候运行只是一个空的导航栏程序,咋都没有,接下来我们添加第二个视图并设置标题文字
新建一个视图,“New file..” -> “UIViewController subclass”,命名为SecondViewController,并勾选“With XIB for user interface”
在RootViewController.xib中添加一个按钮并绑定到(IBAction)displaySecondView
//  AppDelegate.m
 
 
#import "AppDelegate.h"
#import "RootViewController.h"
 
@implementation AppDelegate
 
@synthesize window = _window;
 
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    navController = [[UINavigationController alloc] init];
    RootViewController *rootViewController = [[RootViewController alloc] init];
	// 修改 rootViewController 标题
    rootViewController.title = @"Root View";
 
    // Override point for customization after application launch.
    [navController pushViewController:rootViewController animated:NO];  
    [self.window addSubview:navController.view];
    [self.window makeKeyAndVisible];
 
    [rootViewController release];
 
    return YES;
}

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

//  RootViewController.m
 
#import "RootViewController.h"
#import "SecondViewController.h"
 
@implementation RootViewController
 
...
 
- (void)displaySecondView:(id)sender
{
    SecondViewController *secondViewController = [[SecondViewController alloc] init];
	// 向视图询问它的导航控制器,因为在AppDelegate.m中我们已经在navController中rootViewController,
	// 所以这里我们询问rootViewController的导航控制器就会返回先前navController指针,如果没有就返回空
    [self.navigationController pushViewController:secondViewController animated:YES];
	// 设置 secondViewController 标题
    secondViewController.title = @"Second View";
 
    [secondViewController release];
}
 
@end

运行程序,当点击按钮,动画切换到secondViewController,导航栏自动显示返回rootViewController按钮。

我们看第一张截图,左右各有一个按钮,那么这两个按钮是怎么创建的,UINavigationController上面的区域叫UINavigationItem,UINavigationItem中可以添加UIBarButtonItem,创建界面最好的时机就是在- (void)viewDidLoad方法中.
//  RootViewController.m
 
#import "RootViewController.h"
#import "SecondViewController.h"
 
@implementation RootViewController
 
...
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    UIBarButtonItem *testButton = [[UIBarButtonItem alloc] initWithTitle:@"test" style:UIBarButtonItemStyleBordered target:self action:@selector(testClicked:)];
    self.navigationItem.leftBarButtonItem = testButton;
    [testButton release];
}
...


这时候点击导航栏上的“test”按钮没有任何行为,因为我们还没有创建action testClicked方法
//  RootViewController.m
 
#import "RootViewController.h"
#import "SecondViewController.h"
 
@implementation RootViewController
...
 
- (void)testClicked:(id)sender
{
    NSLog(@"test button clicked.");
}
 
...

有时候我们可能想创建下面的按钮,右边的按钮上面有个小十字,这些系统小图标是iPhone内部预设的,下面来看看这些按钮.

//  RootViewController.m
 
#import "RootViewController.h"
#import "SecondViewController.h"
 
@implementation RootViewController
 
...
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    UIBarButtonItem *testButton = [[UIBarButtonItem alloc] initWithTitle:@"test" style:UIBarButtonItemStyleBordered target:self action:@selector(testClicked:)];
    self.navigationItem.leftBarButtonItem = testButton;
 
    UIBarButtonItem *addButton =[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addClicked:)];
    self.navigationItem.rightBarButtonItem = addButton;
 
    [testButton release];
    [addButton release];
}
 
...
 
- (void)addClicked:(id)sender
{
    NSLog(@"add button clicked.");
}
@end


创建这些按钮很方便,只要打入UIBarButtonSystemItem,Xcode会自动补全,后面列出的都是系统预设按钮。
还有一些按钮按钮和行为,系统已经帮我们定义好了,Edit和Done按钮行为,我们只要实现它就好了
//  RootViewController.m
 
#import "RootViewController.h"
#import "SecondViewController.h"
 
@implementation RootViewController
 
...
 
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    UIBarButtonItem *testButton = [[UIBarButtonItem alloc] initWithTitle:@"test" style:UIBarButtonItemStyleBordered target:self action:@selector(testClicked:)];
    self.navigationItem.leftBarButtonItem = testButton;
 
    self.navigationItem.rightBarButtonItem = self.editButtonItem;
 
    [testButton release];
}
 
...
 
- (void)setEditing:(BOOL)editing animated:(BOOL)animated
{
    [super setEditing:editing animated:animated];
    if (editing) {
        NSLog(@"editing");
    } else {
        NSLog(@"done");
    }
}
 
@end


有时候我们会在导航栏上看到这样的按钮排列,这个又是怎么实现的

//  RootViewController.m
 
#import "RootViewController.h"
#import "SecondViewController.h"
 
@implementation RootViewController
 
...
 
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    UIBarButtonItem *testButton = [[UIBarButtonItem alloc] initWithTitle:@"test" style:UIBarButtonItemStyleBordered target:self action:@selector(testClicked:)];
    self.navigationItem.leftBarButtonItem = testButton;
 
    self.navigationItem.rightBarButtonItem = self.editButtonItem;
    NSArray *segmentButtons = [NSArray arrayWithObjects:@"升序", @"降序", nil];
    UISegmentedControl *segmentedController = [[UISegmentedControl alloc] initWithItems:segmentButtons];
    segmentedController.segmentedControlStyle = UISegmentedControlStyleBar;
    [segmentedController addTarget:self action:@selector(segmentAction:) forControlEvents:UIControlEventValueChanged];
    self.navigationItem.titleView = segmentedController;
 
    [testButton release];
    [segmentedController release];
}
 
...
- (void)segmentAction:(id)sender
{
    switch ([sender selectedSegmentIndex]) {
        case 0:
            NSLog(@"button 0 clicked");
            break;
 
        case 1:
            NSLog(@"button 1 clicked");
            break;
 
        default:
            break;
    }
}
...
@end

返回按钮的定制,如果导航栏的标题很长的话,返回按钮的长度也会变长,而我们并不希望这样的事发生,我们可以设置返回按钮的标题来达到目的,关键是我们要返回哪个视图控制器,就在哪个视图控制器类里修改。
//  RootViewController.m
 
#import "RootViewController.h"
#import "SecondViewController.h"
 
@implementation RootViewController
...
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    ...
    UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"Root" style:UIBarButtonItemStylePlain target:nil action:nil];
    self.navigationItem.backBarButtonItem = backButton;
 
    [backButton release];
}
...
@end

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   发表时间:2012-04-13  
用storyboard开发很爽。
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