系统UITabBar属性设置

设置背景：

1. [_tabBar setBackgroundImage:[UIImage imageNamed:@"bg_tabbar"]];

设置某个Item选中的效果：

1. _tabBar.selectionIndicatorImage = [UIImage imageNamed:@"bar_item_selected"];//设置选中效果图片

设置UITabBarItem文字颜色

1. [[UITabBarItem appearance] setTitleTextAttributes:@{ UITextAttributeTextColor : [UIColor whiteColor] }
2. forState:UIControlStateNormal];
3. [[UITabBarItem appearance] setTitleTextAttributes:@{ UITextAttributeTextColor : [UIColor whiteColor] }
4. forState:UIControlStateHighlighted];

设置UITabBarItem未选中与选中时的图片：

1. [_hotTabItem setFinishedSelectedImage:[UIImage imageNamed:@"1_selected"] withFinishedUnselectedImage:[UIImage imageNamed:@"1"]];
2. [_searchTabItem setFinishedSelectedImage:[UIImage imageNamed:@"2_selected"] withFinishedUnselectedImage:[UIImage imageNamed:@"2"]];
3. [_userTabItem setFinishedSelectedImage:[UIImage imageNamed:@"3_selected"] withFinishedUnselectedImage:[UIImage imageNamed:@"3"]];