Appearance

UIAppearance是一个协议

@protocol UIAppearance 

UIView默认已经遵守了这个协议

NS_CLASS_AVAILABLE_IOS(2_0) @interface UIView : UIResponder 

来看看UIAppearance都有什么方法

+ (instancetype)appearance;

+ (instancetype)appearanceWhenContainedInInstancesOfClasses:(NSArray> *)containerTypes NS_AVAILABLE_IOS(9_0);

+ (instancetype)appearanceForTraitCollection:(UITraitCollection *)trait NS_AVAILABLE_IOS(8_0);

+ (instancetype)appearanceForTraitCollection:(UITraitCollection *)trait whenContainedInInstancesOfClasses:(NSArray> *)containerTypes  NS_AVAILABLE_IOS(9_0);

让某一类控件同时表现某种属性

    //导航条上标题的颜色
    NSDictionary *navbarTitleTextAttributes = @{NSForegroundColorAttributeName:[UIColor whiteColor]};
    [[UINavigationBar appearance] setTitleTextAttributes:navbarTitleTextAttributes];
    [[UINavigationBar appearance] setTintColor:[UIColor redColor]];
    
    //TabBar选中图标的颜色,默认是蓝色
    [[UITabBar appearance] setTintColor:[UIColor greenColor]];
    
    //导航条的背景颜色
    [[UINavigationBar appearance] setBarTintColor:[UIColor yellowColor]];
    
    //TabBar的背景颜色
    [[UITabBar appearance] setBarTintColor:[UIColor brownColor]];
    
    [UISearchBar appearance].tintColor = [UIColor redColor];

    UIPageControl *pageControl = [UIPageControl appearance];
    pageControl.pageIndicatorTintColor = [UIColor magentaColor];
    pageControl.currentPageIndicatorTintColor = [UIColor grayColor];
    
    [[UITextField appearance] setTintColor:[UIColor purpleColor]];
    [[UITextView appearance]  setTintColor:[UIColor darkGrayColor]];

让某一类控件在另一种控件中同时变现某种属性

    //当某个class被包含在另外一个class内时，才修改外观。
    [[UIButton appearanceWhenContainedInInstancesOfClasses:@[[UIView class]]] setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
   
     [[UITextView appearanceWhenContainedInInstancesOfClasses:@[[UISearchBar class]]] setTextColor:[UIColor yellowColor]];

如图所示

Simulator Screen Shot - iPhone 6 - 2019-06-17 at 15.20.21.png