tabBar显示数字气泡

NSArray *tabBarItems = self.tabBar.items;

UITabBarItem *personCenterTabBarItem = [tabBarItems objectAtIndex:3];

personCenterTabBarItem.badgeValue = [NSString stringWithFormat:@"%ld",num];

消除的时候

NSArray *tabBarItems = self.tabBar.items;

UITabBarItem *personCenterTabBarItem = [tabBarItems objectAtIndex:3];

personCenterTabBarItem.badgeValue = nil;