03百思不得姐appearance使用

通过appearance设置统一UITabBarItem属性

apperance介绍

  ***To customize the appearance of all instances of a class, send the relevant appearance modification messages to the appearance proxy for the class. For example, to modify the bar tint color for all UINavigationBar instances:    [[UINavigationBar appearance] setBarTintColor:myColor];    Note for iOS7: On iOS7 the tintColor property has moved to UIView, and now has special inherited behavior described in UIView.h.    This inherited behavior can conflict with the appearance proxy, and therefore tintColor is now disallowed with the appearance proxy.***

    //未选中状态    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];    attrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];    //选中状态    NSMutableDictionary *selectedAttrs = [NSMutableDictionary dictionary];    selectedAttrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];    selectedAttrs[NSForegroundColorAttributeName] = [UIColor darkGrayColor];    //后面带有UI_APPEARANCE的方法，都可以通过appearance对象统一设置设置    UITabBarItem *item = [UITabBarItem appearance];    [item setTitleTextAttributes:attrs forState:UIControlStateNormal];    [item setTitleTextAttributes:selectedAttrs forState:UIControlStateSelected];