ios基础篇（八）——UITabBarController的简单介绍

一、简介

UITabBarController和UINavigationController类似,UITabBarController也可以轻松地管理多个控制器,轻松完成控制器之间的切换,典型的例子就是QQ、微信、微博等应⽤。

二、UITabBarController的使用

1、首先初始化UITabBarController

2、设置UIWindow的rootViewController为UITabBarController

3、创建相应的子控制器（viewcontroller）

4、把子控制器添加到UITabBarController

代码：

//
//  AppDelegate.m
//  微信
//
//  Created by Oran Wu on 15-11-5.
//  Copyright (c) 2015年 Xinxin. All rights reserved.
//

#import "AppDelegate.h"
#import "WeChatViewController.h"
#import "AddressBookViewController.h"
#import "FindViewController.h"
#import "MyViewController.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    //创建Window
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    //创建子控制器
    WeChatViewController *WeChatVC = [[WeChatViewController alloc] init];
    AddressBookViewController *AddressBookVC = [[AddressBookViewController alloc] init];
    FindViewController *FindVC = [[FindViewController alloc] init];
    MyViewController *MyVC = [[MyViewController alloc] init];

    //设置UITabBarButton的图片（normal）与选中时图片（selected）
    UIImage *WeChatImage = [UIImage imageNamed:@"tabbar_mainframe"];
    UIImage *WeChatSeletedImage = [UIImage imageNamed:@"tabbar_mainframeHL"];
    WeChatVC.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"微信" image:WeChatImage selectedImage:WeChatSeletedImage];

    UIImage *AddressImage = [UIImage imageNamed:@"tabbar_contacts"];
    UIImage *AddressSeletedImage = [UIImage imageNamed:@"tabbar_contactsHL"];
    AddressBookVC.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"通讯录" image:AddressImage selectedImage:AddressSeletedImage];

    UIImage *FineImage = [UIImage imageNamed:@"tabbar_discover"];
    UIImage *FineSeletedImage = [UIImage imageNamed:@"tabbar_discoverHL"];
    FindVC.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"发现" image:FineImage selectedImage:FineSeletedImage];
    //提醒数字
    FindVC.tabBarItem.badgeValue = @"";

    UIImage *MyImage = [UIImage imageNamed:@"tabbar_me"];
    UIImage *MySeletedImage = [UIImage imageNamed:@"tabbar_meHL"];
    MyVC.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"我" image:MyImage selectedImage:MySeletedImage];

    //初始化各ViewController的导航控制器
    UINavigationController *WeChatNav = [[UINavigationController alloc] initWithRootViewController:WeChatVC];
    UINavigationController *AddressBookNav = [[UINavigationController alloc] initWithRootViewController:AddressBookVC];
    UINavigationController *FindNav = [[UINavigationController alloc] initWithRootViewController:FindVC];
    UINavigationController *MyNav = [[UINavigationController alloc] initWithRootViewController:MyVC];

    //初始化一个控制器
    UITabBarController *TabBarCtrl = [[UITabBarController alloc] init];
    TabBarCtrl.viewControllers = [NSArray arrayWithObjects:WeChatNav,AddressBookNav,FindNav,MyNav, nil];

    //设置控制器为Window的根控制器
    self.window.rootViewController = TabBarCtrl;
    //设置window的背景颜色
    self.window.backgroundColor = [UIColor whiteColor];

    //设置Window为主窗口并显示出来
    [self.window makeKeyAndVisible];

    // Override point for customization after application launch.
    return YES;
}

三、UITabBar

下方的工具条称为UITabBar ，如果UITabBarController有N个子控制器,那么UITabBar内部就会有N 个UITabBarButton作为子控件与之对应。

注意：UITabBarButton在UITabBar中得位置是均分的，UITabBar的高度为49。

在上面的程序中，UITabBarController有4个子控制器,所以UITabBar中有4个UITabBarButton，UITabBar的结构⼤大致如下图所示：