[BS-03] 统一设置UITabBarController管理的所有VC的tabBarItem图标文字的颜色大小等属性

1.

统一设置UITabBarController管理的所有VC的tabBarItem图标文字的颜色大小等属性

.  统一设置UITabBarController管理的所有VC的tabBarItem图标文字的颜色大小等属性

//设置字体大小及颜色(可变字典才可用[]方法设值)
    NSMutableDictionary *attr = [NSMutableDictionary dictionary];
    attr[NSFontAttributeName] = [UIFont systemFontOfSize:];
    attr[NSForegroundColorAttributeName] = [UIColor grayColor];

    NSMutableDictionary *selectAttr = [NSMutableDictionary dictionary];
    selectAttr[NSFontAttributeName] = [UIFont systemFontOfSize:];//NSFontAttributeName是个const变量，一旦设置了19，后面就不能再改了，这里改为5无效
    selectAttr[NSForegroundColorAttributeName] = [UIColor darkGrayColor];//不能写成NSBackgroundColorAttributeName

    UITabBarItem *item = [UITabBarItem appearance];
    [item setTitleTextAttributes:attr forState:UIControlStateNormal];
    [item setTitleTextAttributes:selectAttr forState:UIControlStateSelected];

. 就不用像下面这样单独给每一个VC.tabBarItem设置字体大小和颜色了
[vc01.tabBarItem setTitleTextAttributes:attr forState:UIControlStateNormal];
    [vc01.tabBarItem setTitleTextAttributes:selectAttr forState:UIControlStateSelected];

[vc02.tabBarItem setTitleTextAttributes:attr forState:UIControlStateNormal];
    [vc02.tabBarItem setTitleTextAttributes:selectAttr forState:UIControlStatelectSelected];

[vc03.tabBarItem setTitleTextAttributes:attr forState:UIControlStateNormal];
    [vc03.tabBarItem setTitleTextAttributes:selectAttr forState:UIControlStateSelected];

2.

原理是：setTitleTextAttributes:forState: 函数后面有备注UI_APPEARANCE_SELECTOR，

可以通过 [Class appearance] setTitleTextAttributes: forState: ]; 来同一设置字体颜色。

//设置UITabBarItem:UIBarItem的颜色属性

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

- (void)setTitleTextAttributes:(nullable NSDictionary<NSString *,id> *)attributes forState:(UIControlState)state NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

- (nullable NSDictionary<NSString *,id> *)titleTextAttributesForState:(UIControlState)state NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR

3.

封装了如下方法，后续要同一设置根控制器UITabBarController管理的各个VC的tabBarItem的字体和颜色，可直接在UITabBarController的viewDidLoad方法中调用[self  setTabBarItemFontAndColor];

//统一设置所有vc的TabBarItem的字体和颜色
- (void)setTabBarItemFontAndColor {

    //设置字体大小及颜色(可变字典才可用此方法)
    NSMutableDictionary *attr = [NSMutableDictionary dictionary];
    attr[NSFontAttributeName] = [UIFont systemFontOfSize:];
    attr[NSForegroundColorAttributeName] = [UIColor grayColor];//NSBackgroundColorAttributeName字体的背景颜色，一般不需要

    NSMutableDictionary *selectAttr = [NSMutableDictionary dictionary];
    selectAttr[NSFontAttributeName] = [UIFont systemFontOfSize:];//NSFontAttributeName是个const变量，一旦设置了19，后面就不能再改了，这里改为5无效
    selectAttr[NSForegroundColorAttributeName] = [UIColor darkGrayColor];//这里不能写成NSBackgroundColorAttributeName

    UITabBarItem *item = [UITabBarItem appearance];
    [item setTitleTextAttributes:attr forState:UIControlStateNormal];
    [item setTitleTextAttributes:selectAttr forState:UIControlStateSelected];//注意此处为UIControlStateSelected,不能写成Highlighted了

    //原理是：setTitleTextAttributes:forState: 函数后面有备注UI_APPEARANCE_SELECTOR，可以通过 [Class appearance] setTitleTextAttributes: forState: ]; 来同一设置字体颜色。
}