2-配置tabbar

先搭建骨架，底部tabbar，切换控制器

object.gif

先创建TabBarController

   UIViewController *vc01 = [[UIViewController alloc] init];
    vc01.tabBarItem.title = @"精华";
    vc01.tabBarItem.image = [UIImage imageNamed:@"tabBar_essence_icon"];
    
    UIImage * image = [UIImage imageNamed:@"tabBar_essence_click_icon"];
    image =  [image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    
    vc01.tabBarItem.selectedImage = image;
    vc01.view.backgroundColor = [UIColor redColor];
    [self addChildViewController:vc01];

    UIViewController *vc02 = [[UIViewController alloc] init];
    vc02.tabBarItem.title = @"新帖";
    vc02.tabBarItem.image = [UIImage imageNamed:@"tabBar_new_icon"];
    vc02.tabBarItem.selectedImage = [UIImage imageNamed:@"tabBar_new_click_icon"];
    vc02.view.backgroundColor = [UIColor orangeColor];
    [self addChildViewController:vc02];
    
    UIViewController *vc03 = [[UIViewController alloc] init];
    vc03.tabBarItem.title = @"关注";
    vc03.tabBarItem.image = [UIImage imageNamed:@"tabBar_friendTrends_icon"];
    vc03.tabBarItem.selectedImage = [UIImage imageNamed:@"tabBar_friendTrends_click_icon"];
    vc03.view.backgroundColor = [UIColor yellowColor];
    [self addChildViewController:vc03];
    
    UIViewController *vc04 = [[UIViewController alloc] init];
    vc04.tabBarItem.title = @"我";
    vc04.tabBarItem.image = [UIImage imageNamed:@"tabBar_me_icon"];
    vc04.tabBarItem.selectedImage = [UIImage imageNamed:@"tabBar_me_click_icon"];
    vc04.view.backgroundColor = [UIColor greenColor];
    [self addChildViewController:vc04];

但是，有没有觉得有大量重复代码，显得很烂啊，稍等再精简一下下吧
由于苹果给tabbar渲染过效果，所以tabbar看起来是

屏幕快照01.png

与要求不符，要做修改
方式一

 UIViewController *vc01 = [[UIViewController alloc] init];
    vc01.tabBarItem.title = @"精华";
    vc01.tabBarItem.image = [UIImage imageNamed:@"tabBar_essence_icon"];
    
    UIImage * image = [UIImage imageNamed:@"tabBar_essence_click_icon"];
    image =  [image imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
  //RenderingMode渲染模式 原始  
    vc01.tabBarItem.selectedImage = image;
    vc01.view.backgroundColor = [UIColor redColor];
    [self addChildViewController:vc01];

效果图

屏幕快照02.png

但是这种代码还是这么多，还得写四个，不想写啊。还有，如果以后这个图片用到其他地方也不想被渲染，就还得写一遍

u=1844650690,767290937&fm=21&gp=0.jpg

好的，那么在找一个简单一点的方法吧，
如图，找到需要的图片选中

屏幕快照03

就好了

屏幕快照04

紧接着还有一个问题，( ⊙o⊙ )?文字怎么还是蓝色的？！既然设置文字和视图属性用tabbarItem，那么文字颜色呢

 UIViewController *vc01 = [[UIViewController alloc] init];
    vc01.tabBarItem.title = @"精华";
    vc01.tabBarItem.image = [UIImage imageNamed:@"tabBar_essence_icon"];
    
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];
    [vc01.tabBarItem setTitleTextAttributes:attrs forState:UIControlStateNormal];
    
    NSMutableDictionary *selectedAttrs = [NSMutableDictionary dictionary];
    selectedAttrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];
    selectedAttrs[NSForegroundColorAttributeName] = [UIColor darkGrayColor];
    [vc01.tabBarItem setTitleTextAttributes:selectedAttrs forState:UIControlStateSelected];

    vc01.tabBarItem.selectedImage = [UIImage imageNamed:@"tabBar_essence_click_icon"];
    vc01.view.backgroundColor = [UIColor redColor];
    [self addChildViewController:vc01];

文字颜色就可以改变了，但是还得写4个

[vc02.tabBarItem setTitleTextAttributes:attrs forState:UIControlStateNormal];
[vc02.tabBarItem setTitleTextAttributes:selectedAttrs forState:UIControlStateSelected];

[vc03.tabBarItem setTitleTextAttributes:attrs forState:UIControlStateNormal];
[vc03.tabBarItem setTitleTextAttributes:selectedAttrs forState:UIControlStateSelected];

[vc04.tabBarItem setTitleTextAttributes:attrs forState:UIControlStateNormal];
[vc04.tabBarItem setTitleTextAttributes:selectedAttrs forState:UIControlStateSelected];

所以要优化一下（一改全改）
进入方法中查看，其结尾有

UI_APPEARANCE_SELECTOR

凡是带有UI_APPEARANCE_SELECTOR宏的，都可以用另一种方法去设置，就是拿到APPEARANCE。那么先把上边01，02，03，04设置文字颜色的方法注释掉，

    //通过appearance统一设置所有UITabBarItem的文字属性
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];
    
    NSMutableDictionary *selectedAttrs = [NSMutableDictionary dictionary];
    selectedAttrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];
    selectedAttrs[NSForegroundColorAttributeName] = [UIColor darkGrayColor];
    //好处就是，只要给appearance设置，以后都是一个效果
   UITabBarItem * item = [UITabBarItem appearance];//appearance外观
    [item setTitleTextAttributes:attrs forState:(UIControlStateNormal)];
    [item setTitleTextAttributes:selectedAttrs forState:(UIControlStateSelected)];
//必须结尾有UI_APPEARANCE_SELECTOR