这个是改变所有tabbar的设置文字颜色属性（appearance）
后面带有UI_APPEARANCE_SELECTOR的方法，都可以通过appearance对象来统一设置。
NSMutableDictionary*dis=[NSMutableDictionarydictionary];
dis[NSFontAttributeName]=[UIFontsystemFontOfSize:17];
dis[NSForegroundColorAttributeName]=[UIColorgrayColor];
UITabBarItem*Item=[UITabBarItemappearance];
[ItemsetTitleTextAttributes:disforState:0];
- (void)setTitleTextAttributes:(nullableNSDictionary *)attributes
forState:(UIControlState)stateNS_AVAILABLE_IOS(5_0)UI_APPEARANCE_SELECTOR;
arc4random_uniform
随机数
自定义的tabbar
UIButtonbutton与图片尺寸一样大
UIButton *but=[UIButton
buttonWithType:UIButtonTypeContactAdd];
[butsetBackgroundImage:@""forState:UIControlStateHighlighted];
but.frame=CGRectMake(0,0, but.currentBackgroundImage.size.width,but.currentBackgroundImage.size.height);
重写tabbar改写layoutsubviews方法(创建tabbar子类)
//kvc设置tabbar
//layoutSubviews, 当我们在某个类的内部调整子视图位置时，需要调用。
隐藏系统自带的tabbar
self.navigationController.hidesBottomBarWhenPushed= YES;
- (void)viewWillAppear:(BOOL)animated
{
[superviewWillAppear:animated];
self.tabBarController.tabBar.hidden=YES;
}
