UIAppearance学习和使用

我们可以通过UIAppearance协议的方法来给整个项目中某一类控件添加全局样式，或者项目中某个类的子类控件添加全局样式。

使用举例

/**
 全局UI设置
 */
- (void)globalSettingUI {
    if (@available(iOS 11.0, *)) {
        [[UIScrollView appearance] setContentInsetAdjustmentBehavior:UIScrollViewContentInsetAdjustmentNever];
        [[UITableView appearance] setEstimatedRowHeight:0];
        [[UITableView appearance] setSectionFooterHeight:0];
        [[UITableView appearance] setSectionHeaderHeight:0];
    }
    [[UITableView appearance] setShowsVerticalScrollIndicator:NO];
    [[UITableView appearance] setBackgroundColor:kAppBackGroundColor];
    [[UICollectionView appearance] setBackgroundColor:kAppBackGroundColor];
    [[UICollectionViewCell appearance] setBackgroundColor:[UIColor whiteColor]];
}

[UIActivityIndicatorView appearanceWhenContainedInInstancesOfClasses:@[[MBProgressHUD class]]].color = [UIColor whiteColor];

UIBarButtonItem *barItem;
 if (@available(iOS 9.0, *)) {
            barItem = [UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[TZImagePickerController class]]];
        } else {
            barItem = [UIBarButtonItem appearanceWhenContainedIn:[TZImagePickerController class], nil];
        }

什么控件能使用UIAppearance协议的方法

遵循UIAppearance协议的类，才能使用协议中的方法。

例如

NS_CLASS_AVAILABLE_IOS(2_0) @interface UIBarItem : NSObject <NSCoding, UIAppearance>

NS_CLASS_AVAILABLE_IOS(2_0) @interface UIView : UIResponder <NSCoding, UIAppearance, UIAppearanceContainer, UIDynamicItem, UITraitEnvironment, UICoordinateSpace, UIFocusItem, CALayerDelegate>

可以知道UIView和UIBarItem是遵循UIAppearance协议的，那么UIView和UIBarItem的子类也是可以使用UIAppearance协议中的方法。当然还有其他的类也遵循。

一般使用的方法

+ (instancetype)appearance;

//  iOS9以下
+ (instancetype)appearanceWhenContainedIn:(nullable Class <UIAppearanceContainer>)ContainerClass, ... NS_REQUIRES_NIL_TERMINATION NS_DEPRECATED_IOS(5_0, 9_0, "Use +appearanceWhenContainedInInstancesOfClasses: instead") __TVOS_PROHIBITED; 

// iOS9以上
+ (instancetype)appearanceWhenContainedInInstancesOfClasses:(NSArray<Class <UIAppearanceContainer>> *)containerTypes NS_AVAILABLE_IOS(9_0);

让某一类控件同时约束

// UITableView不显示垂直线
 [[UITableView appearance] setShowsVerticalScrollIndicator:NO];
// 全部按钮显示白色
[[UIButton appearance] setBackgroundColor:[UIColor whiteColor]];

让一种控件在另一种控件中表现某种属性
// 获取TZImagePickerController 中的UIBarButtonItem类控件,设置

    UIBarButtonItem *barItem;
       if (@available(iOS 9.0, *)) {
            barItem = [UIBarButtonItem appearanceWhenContainedInInstancesOfClasses:@[[TZImagePickerController class]]];
        } else {
            barItem = [UIBarButtonItem appearanceWhenContainedIn:[TZImagePickerController class], nil];
        }
 
    NSMutableDictionary *textAttrs = [NSMutableDictionary dictionary];
    textAttrs[NSForegroundColorAttributeName] = self.barItemTextColor;
    textAttrs[NSFontAttributeName] = self.barItemTextFont;
    [barItem setTitleTextAttributes:textAttrs forState:UIControlStateNormal];