一：首先查看一下关于UITabBarController的定义
NS_CLASS_AVAILABLE_IOS(2_0) @interface UITabBarController : UIViewController <UITabBarDelegate, NSCoding>
//设置控制器数组
@property(nullable, nonatomic,copy) NSArray<__kindof UIViewController *> *viewControllers;
//设置控制器数组 动画
- (void)setViewControllers:(NSArray<__kindof UIViewController *> * __nullable)viewControllers animated:(BOOL)animated;
//选中的控制器
@property(nullable, nonatomic, assign) __kindof UIViewController *selectedViewController;
//选中索引值
@property(nonatomic) NSUInteger selectedIndex;
//当item超过五个时 就会有一个更多
@property(nonatomic, readonly) UINavigationController *moreNavigationController;
@property(nullable, nonatomic, copy) NSArray<__kindof UIViewController *> *customizableViewControllers;
//tab条
@property(nonatomic,readonly) UITabBar *tabBar NS_AVAILABLE_IOS(3_0);
//委托
@property(nullable, nonatomic,weak) id<UITabBarControllerDelegate> delegate;
@end
UITabBarController和UINavigationController一样是用来管理试图控制器的，与导航控制器不同，tabBarController控制器使用数组管理子试图控制器的，并且子试图之间是平等关系，导航控制器所管理的试图控制器之间是在出桟和入桟的关系；
二：UITabBarControllerDelegate委托内容
@protocol UITabBarControllerDelegate <NSObject>
@optional
//返回NO，不能显示选中的视图控制器
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController NS_AVAILABLE_IOS(3_0);
// NSLog(@"视图显示后调用");
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController;
//将要开始自定义item时调用
- (void)tabBarController:(UITabBarController *)tabBarController willBeginCustomizingViewControllers:(NSArray<__kindof UIViewController *> *)viewControllers NS_AVAILABLE_IOS(3_0) __TVOS_PROHIBITED;
//将要结束自定义item时调用
- (void)tabBarController:(UITabBarController *)tabBarController willEndCustomizingViewControllers:(NSArray<__kindof UIViewController *> *)viewControllers changed:(BOOL)changed NS_AVAILABLE_IOS(3_0) __TVOS_PROHIBITED;
//结束自定义item的顺序
- (void)tabBarController:(UITabBarController *)tabBarController didEndCustomizingViewControllers:(NSArray<__kindof UIViewController *> *)viewControllers changed:(BOOL)changed __TVOS_PROHIBITED;
- (UIInterfaceOrientationMask)tabBarControllerSupportedInterfaceOrientations:(UITabBarController *)tabBarController NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
- (UIInterfaceOrientation)tabBarControllerPreferredInterfaceOrientationForPresentation:(UITabBarController *)tabBarController NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
- (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController
interactionControllerForAnimationController: (id <UIViewControllerAnimatedTransitioning>)animationController NS_AVAILABLE_IOS(7_0);
- (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController
animationControllerForTransitionFromViewController:(UIViewController *)fromVC
toViewController:(UIViewController *)toVC NS_AVAILABLE_IOS(7_0);
@end
三：UIViewController (UITabBarControllerItem)分类
@interface UIViewController (UITabBarControllerItem)
//当前视图的UITabBarItem对象
@property(null_resettable, nonatomic, strong) UITabBarItem *tabBarItem;
//如果视图控制器是一个标签栏控制器的子控制器，则返回它。否则返回nil
@property(nullable, nonatomic, readonly, strong) UITabBarController *tabBarController;
@end
四：关于UITabBar的定义
NS_CLASS_AVAILABLE_IOS(2_0) @interface UITabBar : UIView
//委托
@property(nullable,nonatomic,assign) id<UITabBarDelegate> delegate;
//UITabBarItem集合
@property(nullable,nonatomic,copy) NSArray<UITabBarItem *> *items;
//被选中的item
@property(nullable,nonatomic,assign) UITabBarItem *selectedItem;
//批量设置items
- (void)setItems:(nullable NSArray<UITabBarItem *> *)items animated:(BOOL)animated;
- (void)beginCustomizingItems:(NSArray<UITabBarItem *> *)items;
- (BOOL)endCustomizingAnimated:(BOOL)animated;
- (BOOL)isCustomizing;
//渲染色
@property(null_resettable, nonatomic,strong) UIColor *tintColor NS_AVAILABLE_IOS(5_0);
//背景色
@property(nullable, nonatomic,strong) UIColor *barTintColor NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
//被选中的图片选染色
@property(nullable,nonatomic,strong) UIColor *selectedImageTintColor NS_DEPRECATED_IOS(5_0,8_0,"Use tintColor") UI_APPEARANCE_SELECTOR;
//背景图
@property(nullable, nonatomic,strong) UIImage *backgroundImage NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
//选中指示图
@property(nullable, nonatomic,strong) UIImage *selectionIndicatorImage NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
//阴影图
@property(nullable, nonatomic,strong) UIImage *shadowImage NS_AVAILABLE_IOS(6_0) UI_APPEARANCE_SELECTOR;
@property(nonatomic) UITabBarItemPositioning itemPositioning NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
//元素宽度
@property(nonatomic) CGFloat itemWidth NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
//item间隔
@property(nonatomic) CGFloat itemSpacing NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
//风格
@property(nonatomic) UIBarStyle barStyle NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
//是否透明
@property(nonatomic,getter=isTranslucent) BOOL translucent NS_AVAILABLE_IOS(7_0);
@end
UITabBar包含多个UITabBarItem，每⼀个UITabBarItem对应⼀个UIViewController。UITabBar的⾼度是49；系统最多只显⽰5个UITabBarItem，当UITabBarItem超过5个时系统会⾃动增加⼀个更多按钮，点击更多按钮没有在底部出现的按钮会以列表的形式显⽰出来.
五：UITabBarDelegate内容
@protocol UITabBarDelegate<NSObject>
@optional
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item; // called when a new view is selected by the user (but not programatically)
- (void)tabBar:(UITabBar *)tabBar willBeginCustomizingItems:(NSArray<UITabBarItem *> *)items;
- (void)tabBar:(UITabBar *)tabBar didBeginCustomizingItems:(NSArray<UITabBarItem *> *)items;
- (void)tabBar:(UITabBar *)tabBar willEndCustomizingItems:(NSArray<UITabBarItem *> *)items changed:(BOOL)changed;
- (void)tabBar:(UITabBar *)tabBar didEndCustomizingItems:(NSArray<UITabBarItem *> *)items changed:(BOOL)changed;
@end
对于点击哪个UITabBarItem响应事件则是在这个委托里面进行；由于UITabBarController已经遵守了UITabBarDelegate协议，如果有继承UITabBarController已经可以直接运用UITabBarDelegate里面的内容；
知识点1：iOS 点击UITabBar触发刷新
平常我们在切换UITabBarController底部菜单时，它是不会有刷新的功能；如果要实现刷新的效果可以如下实现；原理如下,在监听UITabBar点击的方法中判断本次点击的UITabBarItem和上次点击的是否一样，如果一样就发出通知,首先需要自定义一个UITabBarController (比如LLTabBarController);要判断本次点击的UITabBarItem和上次点击的是否一样，就需要定义一个属性记录下来上次点击的UITabBarItem，并在viewWillAppear:方法中给该属性赋值默认的UITabBarItem
/** 之前被选中的UITabBarItem */
@property (nonatomic, strong) UITabBarItem *lastItem;
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
// 将默认被选中的tabBarItem保存为属性
self.lastItem = self.tabBar.selectedItem;
}
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
// 判断本次点击的UITabBarItem是否和上次的一样
if (item == self.lastItem) { // 一样就发出通知
[[NSNotificationCenter defaultCenter] postNotificationName:@"LLTabBarDidClickNotification" object:nil userInfo:nil];
}
// 将这次点击的UITabBarItem赋值给属性
self.lastItem = item;
}
在需要实现点击UITabBar触发刷新功能的控制器中监听通知
- (void)viewDidLoad {
[super viewDidLoad];
// 监听UITabBarItem被重复点击时的通知
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(tabBarDidClick) name:@"LLTabBarDidClickNotification" object:nil];
}
- (void)tabBarDidClick
{
// 如果本控制器的view显示在最前面，就下拉刷新
if ([self.view isShowingOnKeyWindow]) { // 判断一个view是否显示在根窗口上，该方法在UIView的分类中实现
[self.tableView.header beginRefreshing]; // MJRefresh
}
}
判断一个view是否显示在根窗口上
/** 该方法在UIView的分类中实现 */
- (BOOL)isShowingOnKeyWindow
{
UIWindow *keyWindow = [UIApplication sharedApplication].keyWindow;
// 把这个view在它的父控件中的frame(即默认的frame)转换成在window的frame
CGRect convertFrame = [self.superview convertRect:self.frame toView: keyWindow];
CGRect windowBounds = keyWindow.bounds;
// 判断这个控件是否在主窗口上（即该控件和keyWindow有没有交叉）
BOOL isOnWindow = CGRectIntersectsRect(convertFrame, windowBounds);
// 再判断这个控件是否真正显示在窗口范围内（是否在窗口上，是否为隐藏，是否透明）
BOOL isShowingOnWindow = (self.window == keyWindow) && !self.isHidden && (self.alpha > 0.01) && isOnWindow;
return isShowingOnWindow;
}
在控制器销毁时要移除通知
- (void)dealloc{ // 移除通知
[[NSNotificationCenter defaultCenter] removeObserver:self];}
六：UITabBarItem的定义
NS_CLASS_AVAILABLE_IOS(2_0) @interface UITabBarItem : UIBarItem
- (instancetype)init NS_DESIGNATED_INITIALIZER;
//初始化几中方式
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;
- (instancetype)initWithTitle:(nullable NSString *)title image:(nullable UIImage *)image tag:(NSInteger)tag;
//初始化 标是 图标 选中图标
- (instancetype)initWithTitle:(nullable NSString *)title image:(nullable UIImage *)image selectedImage:(nullable UIImage *)selectedImage NS_AVAILABLE_IOS(7_0);
- (instancetype)initWithTabBarSystemItem:(UITabBarSystemItem)systemItem tag:(NSInteger)tag;
//给当前的分栏控制器的item设置一个选中状态的图片
@property(nullable, nonatomic,strong) UIImage *selectedImage NS_AVAILABLE_IOS(7_0);
//角标
@property(nullable, nonatomic, copy) NSString *badgeValue;
//IOS7以后过期
- (void)setFinishedSelectedImage:(nullable UIImage *)selectedImage withFinishedUnselectedImage:(nullable UIImage *)unselectedImage NS_DEPRECATED_IOS(5_0,7_0,"Use initWithTitle:image:selectedImage: or the image and selectedImage properties along with UIImageRenderingModeAlwaysOriginal");
//IOS7以后过期
- (nullable UIImage *)finishedSelectedImage NS_DEPRECATED_IOS(5_0,7_0);
//IOS7以后过期
- (nullable UIImage *)finishedUnselectedImage NS_DEPRECATED_IOS(5_0,7_0);
//文字的偏移
@property (nonatomic, readwrite, assign) UIOffset titlePositionAdjustment NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
@end
知识点1：tabBarItem相关属性运用
1) 用来控制一组控制器的切换，类似选项卡，每个Tab控制一个试图控制器，点击哪个tab就显示对应的试图控制器，当前的试图控制器
2) 每个tabBarItem都可以设置title、image/selectedImages、badgeValue
例如：
（1）.给当前的分栏控制器的item设置一个标题
self.tabBarItem.title = @"我的";
（2）.给当前的分栏控制器的item设置一个图片
self.tabBarItem.image = [UIImage imageNamed:@"tab_buddy_nor@2x"];
（3）.给当前的分栏控制器的item设置一个选中状态的图片
self.tabBarItem.selectedImage = [UIImage imageNamed:@"tab_me_nor@2x"];//@2x表示给高清屏 30*30的效果好
self.tabBarItem.badgeValue = @"new";//在小图标的上面家字体加字体
3) 设置选中的颜色
分栏控制器.tabBar.tintColor
self.tabBarController.tabBar.tintColor = [UIColor redColor];
3) TabBar只能显示五个tab Item，如果超过五个则会自动生成个Morede 标签显示剩余的Tab,这些Tab可以通过编辑显示在UITabBar上（打开页面后自动显示在界面，点击tabBar右边）
4) 自定义Item
[UITabBarItem alloc]initWithTitle: image: tag:
[UITabBarItem alloc]initWithTabBarSystemItem:tag:
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