UIApearance 简介
UIApearance 简介
UIApearance 实际上是一个协议，我们可以用它来获取一个类的外观代理 (appearance proxy) 。为什么说是一个类，而不明确说是一个视图或控件呢？这是因为有些非视图对象 (如UIBarButtonItem) 也可以实现这个协议，来定义其所包含的视图对象的外观。我们可以给这个类的外观代理发送一个修改消息，来自定义一个类的实例的外观。
我们以系统定义的控件 UIButton 为例，根据我们的使用方式，可以通过 UIAppearance 修改整个应用程序中所有 UIButton 的外观，也可以修改某一特定容器类中所有 UIButton 的外观 (如 UIBarButtonItem)。不过需要注意的是，这种修改只会影响到那些执行 UIAppearance 操作之后添加到我们的视图层级架构中的视图或控件，而不会影响到修改之前就已经添加的对象。因此，如果要修改特定的视图，先确保该视图在使用 UIAppearance 后才通过 addSubview 添加到视图层级架构中。
UIAppearance 使用
@protocol UIAppearance <NSObject>
/* 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]; // 全局设置 UINavigationBar 实例的外观
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.
*/
+ (instancetype)appearance; // 获取 appearance proxy
// 获取在不同类中的 appearance proxy
/* To customize the appearances for instances of a class contained within an instance of a container class, or instances in a hierarchy, use +appearanceWhenContainedInInstancesOfClasses: for the appropriate appearance proxy. For example:
[[UINavigationBar appearanceWhenContainedInInstancesOfClasses:@[[UISplitViewController class]]] setBarTintColor:myColor]; // 设置 UINavigationBar 在 UISplitViewController 及其子类中的 tintColor
[[UINavigationBar appearanceWhenContainedInInstancesOfClasses:@[[UITabBarController class], [UISplitViewController class]]] setBarTintColor:myTabbedNavBarColor];
In any given view hierarchy the outermost appearance proxy wins. Specificity (depth of the chain) is the tie-breaker.
In other words, the containment statement is treated as a partial ordering. Given a concrete ordering (actual subview hierarchy), we select the partial ordering that is the first unique match when reading the actual hierarchy from the window down.
*/
+ (instancetype)appearanceWhenContainedIn:(nullable Class <UIAppearanceContainer>)ContainerClass, ... NS_REQUIRES_NIL_TERMINATION NS_DEPRECATED_IOS(5_0, 9_0, "Use +appearanceWhenContainedInInstancesOfClasses: instead") __TVOS_PROHIBITED;
+ (instancetype)appearanceWhenContainedInInstancesOfClasses:(NSArray<Class <UIAppearanceContainer>> *)containerTypes NS_AVAILABLE_IOS(9_0);
// 获取在不同 size class 下的 appearance proxy
+ (instancetype)appearanceForTraitCollection:(UITraitCollection *)trait NS_AVAILABLE_IOS(8_0);
+ (instancetype)appearanceForTraitCollection:(UITraitCollection *)trait whenContainedIn:(nullable Class <UIAppearanceContainer>)ContainerClass, ... NS_REQUIRES_NIL_TERMINATION NS_DEPRECATED_IOS(8_0, 9_0, "Use +appearanceForTraitCollection:whenContainedInInstancesOfClasses: instead") __TVOS_PROHIBITED;
+ (instancetype)appearanceForTraitCollection:(UITraitCollection *)trait whenContainedInInstancesOfClasses:(NSArray<Class <UIAppearanceContainer>> *)containerTypes NS_AVAILABLE_IOS(9_0);
@end
