利用系统自带的UITabBarController纯代码搭建TabBar

1.创建UITabBarController文件，例如夜宵App的TabBar，文件名定义为YeXiaoTabBarController

2.创建完成后，在.m文件的viewDidLoad方法中写入以下代码：

    self.tabBar.translucent = NO;
    self.tabBar.tintColor = [UIColor whiteColor];
    
    UIImage *background = [[UIImage imageNamed:@"背景图片"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 10, 10) resizingMode:UIImageResizingModeStretch];
    [self.tabBar setBackgroundImage:background];
    
    UIImage *selectedBackground = [[UIImage imageNamed:@"选中后的背景图片"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 10, 10) resizingMode:UIImageResizingModeStretch];
    [self.tabBar setSelectionIndicatorImage:selectedBackground];

3.创建TabBar的各个item对应的子控制器，例如店铺（ShopViewController）、个人设置（SetViewComtroller）等等，并在子控制器中重写init方法，例如个人设置中重写init方法代码如下：

-(instancetype)init{
    if (self = [super init]) {
        self.title = @"个人设置";
        self.tabBarItem.image = [UIImage imageNamed:@"原始图片"];
        self.tabBarItem.selectedImage = [UIImage imageNamed:@"选中后的图片"];
    }
    return self;
}

4.将各个子控制器添加到YeXiaoTabBarController中，继续在.m文件的viewDidLoad方法中写入以下代码：

    ShopViewController *shopVC = [[ShopViewController alloc]init];
    ScanViewController *scanVC = [[ScanViewController alloc]init];
    SetViewController *setVC = [[SetViewController alloc]init];
    
    UINavigationController *shopNavi = [[UINavigationController alloc]initWithRootViewController:shopVC];
    UINavigationController *scanNavi = [[UINavigationController alloc]initWithRootViewController:scanVC];
    UINavigationController *setNavi = [[UINavigationController alloc]initWithRootViewController:setVC];
    
    self.viewControllers = @[shopNavi ,scanNavi ,setNavi];