ios学习：UINavigationController导航

文件目录如下：基本导航顺序： root -> First -> Second -> Third。其中，FirstViewController作为 navigation堆栈的rootview

1、创建navigation。

如果是想直接把navigation导航作为项目一开始的跟视图，把RootViewController.h文件里的nav属性放到AppDelegate.h里即可，再把RootViewController.m文件里的action的代码复制到 AppDelegate.m里的didFinishLaunchingWithOptions 方法里，最后把 self.window.rootViewController 设置 UINavigationController类型的属性nav即可

在RootViewController.h文件

#import <UIKit/UIKit.h>
@class FirstViewController;

@interface RootViewController : UIViewController

@property (strong, nonatomic) UINavigationController *nav;

- (IBAction)btnClick:(UIButton *)sender;

@end

在RootViewController.m 文件里的随意一个自定义action里：

- (IBAction)btnClick:(UIButton *)sender {
    
    //创建一个viewcontroller
    FirstViewController *fristview =[[[FirstViewController alloc] init] autorelease];
   
    
    //初始化UINavigationController(方式一)
    self.nav = [[[UINavigationController alloc] initWithRootViewController:fristview] autorelease];
    
    
    //初始化UINavigationController(方式二)
  //  self.nav = [[[UINavigationController alloc] init] autorelease];
  //  [self.nav pushViewController:fristview animated:YES];

    
    //初始化UINavigationController(方式三,失败,xib文件加载失败,原因暂时不明)
   // self.nav = [[[UINavigationController alloc] initWithNibName:@"FirstViewController" bundle:nil] autorelease];
    
    
    //跳转到FirstView页面
    [self presentViewController:self.nav animated:YES completion:nil];
    
    
    //这种写法一般用于往view里添加一些小控件,如button  label textField之类的,不适宜用于页面跳转
    // [self.view addSubview:self.nav.view];
    
    
}

2、设置viewcontroller的navigationItem属性和 toolbar、toolbarItem

（1）firstViewcontroller的navigation属性和toolbarItem属性。代码在firstviewcontroller.m的viewdidLoad方法里

每个viewcontroller都有一个navigationItem属性（只在被加载到导航堆栈里才有效），navigationItem属性里又有5个属性：UIBarButtonItem类型的leftBarButtonItem、rightBarButtonItem和backBarButtonItem，NSString类型的title（或者viewcontroller属性的titleView）、prompt。

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    
    //下面两句代码的效果一样,但貌似设置了navigationItem.title 后 title就会被不起作用了
    self.navigationItem.title =  @"首页123";
    self.title = @"首页";
    
    //在title上面再加多一行,但这样子就会造成导航栏的宽度变宽
  //  self.navigationItem.prompt = @"prompt";
    
    //设置rightbarbuttonitem
    UIBarButtonItem *rightbar = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(btnClick:)] autorelease];

    self.navigationItem.rightBarButtonItem = rightbar;

    //修改backbarbuttonitem的title.这个backbarbutton是显示在下一个push进来的view的tabbar的左边的
    //action可以设置为nil,这是的动作就是默认的动作,也就是返回到这个view
    self.navigationItem.backBarButtonItem = [[[UIBarButtonItem alloc] initWithTitle:@"back" style:UIBarButtonItemStylePlain target:self action:nil] autorelease];
    
    
    
    //设置toolbar是否可见(对整个navigation堆栈里的view起作用,起全局作用)
    self.navigationController.toolbarHidden = NO;
    
    UIBarButtonItem *three = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:nil action:nil];
    UIBarButtonItem *four = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemEdit target:nil action:nil];
    UIBarButtonItem *flexItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
    
    //toolbar是整个navigation堆栈里的view共同的,但toolbar上面的items却是每个view单独拥有的
    //现在只是设置了当前view的toolbaritem,与其他view的toolbaritme是没有关系的
    [self setToolbarItems:[NSArray arrayWithObjects:flexItem, three, flexItem, four, flexItem, nil]];
    
    [three release];
    [four release];
    [flexItem release];
   
    
}

页面效果如下：

(2)、secondviewcontroller的navigationItem和toolbarItem

代码在viewdidLoad方法里

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

    //设置左右barbutton
    UIBarButtonItem *rightbar = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(gotoThird:)] autorelease];
    
    UIBarButtonItem *leftbar = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(gotoThird:)] autorelease];
    
    self.navigationItem.rightBarButtonItem = rightbar;
    self.navigationItem.leftBarButtonItem = leftbar;
    
    //当前view在navigation堆栈里不是rootview,所以把该viewpush到navigation堆栈里时,tabbar左边会显示backbarbutton
    //如果给当前view设置了leftbarbutton,会把把backbarbutton覆盖掉,想同时显示两者,需如下设置:
    self.navigationItem.leftItemsSupplementBackButton = YES;

    
    
    //设置当前view的toolbar可见.因为有可能从一个toolbar不可见的view导航到当前view
    self.navigationController.toolbarHidden = NO;
    
}

效果如下：

(3)、thirdviewcontroller的navigationItem和toolbaritem

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.title = @"第三页";
    // Do any additional setup after loading the view from its nib.
    
    //隐藏当前view的toolbar
    self.navigationController.toolbarHidden = YES;
    
    //设置toolbar
    UIBarButtonItem *rightbar = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(goToRootView)] autorelease];
    
    self.navigationItem.rightBarButtonItem = rightbar;
    
   // NSArray *array = @[@"排骨", @"牛排"];
    
    //设置titleview,会覆盖title
    UISegmentedControl *segment = [[[UISegmentedControl alloc] initWithItems:@[@"排骨", @"牛扒"] ] autorelease];
    segment.segmentedControlStyle = UISegmentedControlSegmentCenter;
    
    self.navigationItem.titleView = segment;
}

效果如下：

barButtonItem的style及效果对应如下：