标签视图

一、标签视图控制器 UITabBarController
二、UITabBar
三、UITabBarItem
四、三大视图控制器综合使用
五、Block高级

UITabBarController组成
Tab Bar Controller View、custom Content、Tab bar
重要属性

UITabBar
tabBar是UITabBar对象，包含多个UITabBarItem,每一个tabBarItem对应一个ViewController。tabBar高度49
当tabBarItem超过5个，系统会自动增加一个更多按钮，点击更多按钮显示为在列表上显示的按钮
tabBar属性：tintColor、barTintColor、图像属性
TabBarItem可以设置title、image、badgeVague，也可以是使用系统样式创建TabBarItem；
如果想通过一键设定所有视图控制器的的颜色，例如QQ一键换肤，可以用UIAppearance.

UITabBarController是项目开发常见布局，与UINavigationController不同，它的ViewControllers是并列的，UINavigationController是层次性的
UITabBarController、UINavigationController、UItableViewController通常组合出现。
UITabBarController、UINavigationController可以相互套嵌

Block高级
1、Block是匿名函数，能够实现函数回调功能
2、用于页面之间通信，同时可以进行传值。
3、定义属性接受Block，必须用copy修饰，retain无效，会造成野指针问题
4、block在某个方法中定义时存储在栈区，在另个类中使用需要进行copy，存储在堆区
5、当不使用block时需要销毁，在dealloc中要使用对应的Block_Release()

注意事项：循环使用的问题
在Block实现部分，不能直接使用实例变量，self调用属性，因为Block会造成self引用计数加1，最终导致循环引用问题。
使用__Block解决循环引用的问题

代码实例

#import "AppDelegate.h"
#import "FirstViewController.h"
#import "SecondViewController.h"
#import "ThirdViewController.h"
#import "FourthViewController.h"

@interface AppDelegate ()

@end

@implementation AppDelegate
- (void)dealloc
{
    [_window release ];
    [super   dealloc ];
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    self.window =[[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];

//第一个视图控制器
    FirstViewController * firstVC =[[FirstViewController alloc]init];

    //设置tabBarButton上的标题
    //firstVC.tabBarItem.title = @"首页";
    //自己创建tabBarItem
    firstVC.tabBarItem = [[[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemSearch tag:101 ]autorelease];
 //第二个视图控制器对象

    SecondViewController * secondVC =[[SecondViewController alloc]init];
    secondVC.tabBarItem = [[[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemContacts tag:102]autorelease];

//第三个视图控制器

    ThirdViewController * thirdVC =[[ThirdViewController alloc]init];

    thirdVC.tabBarItem = [[UITabBarItem alloc]initWithTitle:@"message" image:[UIImage imageNamed:@"123.png" ] tag:103];
    thirdVC.tabBarItem.badgeValue = @"99+";


    UITabBarController * TBC = [[UITabBarController alloc]init  ];
    _window.rootViewController    = TBC;
   //给thirdVC添加导航控制器
    UINavigationController * NC1 = [[UINavigationController alloc]initWithRootViewController:thirdVC];


//第四个视图控制器对象
    FourthViewController * fourthVC = [[FourthViewController alloc]init];
    fourthVC.tabBarItem = [[UITabBarItem alloc]initWithTitle:@"" image:[UIImage imageNamed:@"1234.png" ]selectedImage:[UIImage imageNamed:@"123.png"]];
    //fourthVC.



    //将firstVC添加到数组中，接受管理
    TBC.viewControllers = @[firstVC,secondVC,NC1 ,fourthVC];

#pragma mark -----设置tabbar相关的属性（颜色，控件的颜色）；
    //1.设置tabbar颜色
    TBC .tabBar.barTintColor = [UIColor brownColor];
    //2.设置tabbar上控件的颜色
    TBC.tabBar.tintColor = [UIColor purpleColor];
    //3.设置默认选中哪个UITableBarButton
    TBC.selectedIndex = 2;
    //设置代理
    TBC.delegate = self;


    //释放
    [firstVC release];
    [secondVC release];
    [TBC release];

    [_window makeKeyAndVisible ];
    [_window release];
    return YES;
}

#pragma mark-----实现协议中的方法
//当tabBar上某个tabBarButton被点中时，触发这个方法
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
    NSLog(@"%@",[viewController class]);
    viewController.tabBarItem.badgeValue = nil;
}

Block相关用法示例

RootViewController.m
#import "RootViewController.h"
#import "FirstViewController.h"
@interface RootViewController ()

@end

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.view.backgroundColor    = [UIColor purpleColor];

    [self createRightBarButtonItem];
#pragma mark-----创建rightBarButtonItem
    [self createButton];
}

- (void)createButton
{
    UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = CGRectMake(100, 100, 60, 40);
    button.backgroundColor = [UIColor redColor];
    [button addTarget:self action:@selector(didClickButton:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}
- (void)didClickButton:(UIButton *)button
{
    FirstViewController * firstVC = [[FirstViewController alloc]init];
    [self.navigationController pushViewController:firstVC animated:YES];
    [firstVC release];
    //或者[self didClickRightBI:nil];
    //②.当点击Button按钮的时候，调用Block，调用的形式：Block变量名（实参列表）

    [firstVC view];
    _block(button.backgroundColor);

}

- (void) createRightBarButtonItem
{
    UIBarButtonItem * BI =  [[UIBarButtonItem alloc]initWithTitle:@"PUSH" style:UIBarButtonItemStylePlain target:self action:@selector(didClickBI:)];
    self.navigationItem.rightBarButtonItem = BI;

     [BI release];
}

- (void)didClickBI:(UIBarButtonItem *)BI
{
    FirstViewController  * firstVC =[[FirstViewController alloc]init];
    [self.navigationController pushViewController:firstVC animated:YES];
    [firstVC release];


}
//firstViewController.h文件

#import <UIKit/UIKit.h>
typedef void(^BLOCK)(UIColor*);
@interface FirstViewController : UIViewController

@end
//firstViewController.m文件

#import "FirstViewController.h"
#import "RootViewController.h"
//typedef int(^BLOCK)(int, int);
@interface FirstViewController ()
@property(nonatomic,copy)BLOCK  block;
@end

@implementation FirstViewController

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

    self.view.backgroundColor= [UIColor yellowColor];


   RootViewController * controller =(RootViewController*)self.navigationController.viewControllers[0];

    controller.block  = ^void(UIColor * color){

        self.view.backgroundColor = color;

    };
}