1.每个UIViewController都有一个tabBarItem

@interface UIViewController (UITabBarControllerItem)

@property(null_resettable, nonatomic, strong) UITabBarItem *tabBarItem;

2.UITabBarItem(子类)

NS_CLASS_AVAILABLE_IOS(2_0) @interface UITabBarItem : UIBarItem

3.UIBarItem(父类)

NS_CLASS_AVAILABLE_IOS(2_0) @interface UIBarItem : NSObject <NSCoding, UIAppearance>
// 设置tabBarItem的文字
@property(nullable, nonatomic,copy)             NSString    *title;        // default is nil

4.示例代码

• 示例代码1

//创建子控制器
UIViewController *c1=[[UIViewController alloc]init];
c1.view.backgroundColor=[UIColor grayColor];
c1.view.backgroundColor=[UIColor greenColor];
c1.tabBarItem.title=@"消息";
c1.tabBarItem.image=[UIImage imageNamed:@"tab_recent_nor"];
c1.tabBarItem.badgeValue=@"123";

• 示例代码2

/**
 往tabbar添加一个子控制器

 @param childController 子控制器
 @param title 子控制器的title
 @param image tabbar的图片名字
 */
- (void)addChildViewController:(UIViewController *)childController title: (NSString *)title image: (NSString *)image {
    childController.title = title;
    
    // 设置tabbarItem的文字大小和颜色
    [childController.tabBarItem setTitleTextAttributes:@{NSFontAttributeName: [UIFont systemFontOfSize:11], NSForegroundColorAttributeName: globalColor} forState:UIControlStateSelected];
    [childController.tabBarItem setTitleTextAttributes:@{NSFontAttributeName: [UIFont systemFontOfSize:11], NSForegroundColorAttributeName: [UIColor darkGrayColor]} forState:UIControlStateNormal];
    
    // 设置tabbar的图片
    // 如果没有传图片(中间的占位控制器), 就不设置tabbar的image
    if (image != nil) {
        childController.tabBarItem.image = [[UIImage imageNamed:[NSString stringWithFormat:@"tabbar_%@", image]] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
        childController.tabBarItem.selectedImage = [[UIImage imageNamed:[NSString stringWithFormat:@"tabbar_%@_selected", image]] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    }
    
    UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:childController];
    
    [self addChildViewController:navController];
}

• 示例代码3

// 设置tabbarItem的文字大小和颜色
[childController.tabBarItem setTitleTextAttributes:@{NSFontAttributeName: [UIFont systemFontOfSize:11], NSForegroundColorAttributeName: globalColor} forState:UIControlStateSelected];
[childController.tabBarItem setTitleTextAttributes:@{NSFontAttributeName: [UIFont systemFontOfSize:11], NSForegroundColorAttributeName: [UIColor darkGrayColor]} forState:UIControlStateNormal];

• 很多属性的设置都可以在这个文件里找到

NSAttributedString.h

5.添加子控制器到UITabBarController中

• 方式一

[tb addChildViewController:c1];
[tb addChildViewController:c2];

• 方式二

tb.viewControllers=@[c1,c2,c3,c4];

6.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

UITabBar

UITabBarItem的设置