一：首先查看一下關于UITabBarController的定義
NS_CLASS_AVAILABLE_IOS(2_0) @interface UITabBarController : UIViewController <UITabBarDelegate, NSCoding>
//設置控制器數(shù)組
@property(nullable, nonatomic,copy) NSArray<__kindof UIViewController *> *viewControllers;
//設置控制器數(shù)組 動畫
- (void)setViewControllers:(NSArray<__kindof UIViewController *> * __nullable)viewControllers animated:(BOOL)animated;
//選中的控制器
@property(nullable, nonatomic, assign) __kindof UIViewController *selectedViewController;
//選中索引值
@property(nonatomic) NSUInteger selectedIndex;
//當item超過五個時 就會有一個更多
@property(nonatomic, readonly) UINavigationController *moreNavigationController;
@property(nullable, nonatomic, copy) NSArray<__kindof UIViewController *> *customizableViewControllers;
//tab條
@property(nonatomic,readonly) UITabBar *tabBar NS_AVAILABLE_IOS(3_0);
//委托
@property(nullable, nonatomic,weak) id<UITabBarControllerDelegate> delegate;
@end
UITabBarController和UINavigationController一樣是用來管理試圖控制器的，與導航控制器不同，tabBarController控制器使用數(shù)組管理子試圖控制器的，并且子試圖之間是平等關系，導航控制器所管理的試圖控制器之間是在出桟和入桟的關系；
二：UITabBarControllerDelegate委托內(nèi)容
@protocol UITabBarControllerDelegate <NSObject>
@optional
//返回NO，不能顯示選中的視圖控制器
- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController NS_AVAILABLE_IOS(3_0);
// NSLog(@"視圖顯示后調(diào)用");
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController;
//將要開始自定義item時調(diào)用
- (void)tabBarController:(UITabBarController *)tabBarController willBeginCustomizingViewControllers:(NSArray<__kindof UIViewController *> *)viewControllers NS_AVAILABLE_IOS(3_0) __TVOS_PROHIBITED;
//將要結(jié)束自定義item時調(diào)用
- (void)tabBarController:(UITabBarController *)tabBarController willEndCustomizingViewControllers:(NSArray<__kindof UIViewController *> *)viewControllers changed:(BOOL)changed NS_AVAILABLE_IOS(3_0) __TVOS_PROHIBITED;
//結(jié)束自定義item的順序
- (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)分類
@interface UIViewController (UITabBarControllerItem)
//當前視圖的UITabBarItem對象
@property(null_resettable, nonatomic, strong) UITabBarItem *tabBarItem;
//如果視圖控制器是一個標簽欄控制器的子控制器，則返回它。否則返回nil
@property(nullable, nonatomic, readonly, strong) UITabBarController *tabBarController;
@end
四：關于UITabBar的定義
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;
//被選中的item
@property(nullable,nonatomic,assign) UITabBarItem *selectedItem;
//批量設置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;
//被選中的圖片選染色
@property(nullable,nonatomic,strong) UIColor *selectedImageTintColor NS_DEPRECATED_IOS(5_0,8_0,"Use tintColor") UI_APPEARANCE_SELECTOR;
//背景圖
@property(nullable, nonatomic,strong) UIImage *backgroundImage NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
//選中指示圖
@property(nullable, nonatomic,strong) UIImage *selectionIndicatorImage NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
//陰影圖
@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;
//元素寬度
@property(nonatomic) CGFloat itemWidth NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
//item間隔
@property(nonatomic) CGFloat itemSpacing NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
//風格
@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包含多個UITabBarItem，每?個UITabBarItem對應?個UIViewController。UITabBar的?度是49；系統(tǒng)最多只顯?5個UITabBarItem，當UITabBarItem超過5個時系統(tǒng)會?動增加?個更多按鈕，點擊更多按鈕沒有在底部出現(xiàn)的按鈕會以列表的形式顯?出來.
五：UITabBarDelegate內(nèi)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
對于點擊哪個UITabBarItem響應事件則是在這個委托里面進行；由于UITabBarController已經(jīng)遵守了UITabBarDelegate協(xié)議，如果有繼承UITabBarController已經(jīng)可以直接運用UITabBarDelegate里面的內(nèi)容；
知識點1：iOS 點擊UITabBar觸發(fā)刷新
平常我們在切換UITabBarController底部菜單時，它是不會有刷新的功能；如果要實現(xiàn)刷新的效果可以如下實現(xiàn)；原理如下,在監(jiān)聽UITabBar點擊的方法中判斷本次點擊的UITabBarItem和上次點擊的是否一樣，如果一樣就發(fā)出通知,首先需要自定義一個UITabBarController (比如LLTabBarController);要判斷本次點擊的UITabBarItem和上次點擊的是否一樣，就需要定義一個屬性記錄下來上次點擊的UITabBarItem，并在viewWillAppear:方法中給該屬性賦值默認的UITabBarItem
/** 之前被選中的UITabBarItem */
@property (nonatomic, strong) UITabBarItem *lastItem;
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
// 將默認被選中的tabBarItem保存為屬性
self.lastItem = self.tabBar.selectedItem;
}
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
// 判斷本次點擊的UITabBarItem是否和上次的一樣
if (item == self.lastItem) { // 一樣就發(fā)出通知
[[NSNotificationCenter defaultCenter] postNotificationName:@"LLTabBarDidClickNotification" object:nil userInfo:nil];
}
// 將這次點擊的UITabBarItem賦值給屬性
self.lastItem = item;
}
在需要實現(xiàn)點擊UITabBar觸發(fā)刷新功能的控制器中監(jiān)聽通知
- (void)viewDidLoad {
[super viewDidLoad];
// 監(jiān)聽UITabBarItem被重復點擊時的通知
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(tabBarDidClick) name:@"LLTabBarDidClickNotification" object:nil];
}
- (void)tabBarDidClick
{
// 如果本控制器的view顯示在最前面，就下拉刷新
if ([self.view isShowingOnKeyWindow]) { // 判斷一個view是否顯示在根窗口上，該方法在UIView的分類中實現(xiàn)
[self.tableView.header beginRefreshing]; // MJRefresh
}
}
判斷一個view是否顯示在根窗口上
/** 該方法在UIView的分類中實現(xiàn) */
- (BOOL)isShowingOnKeyWindow
{
UIWindow *keyWindow = [UIApplication sharedApplication].keyWindow;
// 把這個view在它的父控件中的frame(即默認的frame)轉(zhuǎn)換成在window的frame
CGRect convertFrame = [self.superview convertRect:self.frame toView: keyWindow];
CGRect windowBounds = keyWindow.bounds;
// 判斷這個控件是否在主窗口上（即該控件和keyWindow有沒有交叉）
BOOL isOnWindow = CGRectIntersectsRect(convertFrame, windowBounds);
// 再判斷這個控件是否真正顯示在窗口范圍內(nèi)（是否在窗口上，是否為隱藏，是否透明）
BOOL isShowingOnWindow = (self.window == keyWindow) && !self.isHidden && (self.alpha > 0.01) && isOnWindow;
return isShowingOnWindow;
}
在控制器銷毀時要移除通知
- (void)dealloc{ // 移除通知
[[NSNotificationCenter defaultCenter] removeObserver:self];}
六：UITabBarItem的定義
NS_CLASS_AVAILABLE_IOS(2_0) @interface UITabBarItem : UIBarItem
- (instancetype)init NS_DESIGNATED_INITIALIZER;
//初始化幾中方式
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;
- (instancetype)initWithTitle:(nullable NSString *)title image:(nullable UIImage *)image tag:(NSInteger)tag;
//初始化 標是 圖標 選中圖標
- (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;
//給當前的分欄控制器的item設置一個選中狀態(tài)的圖片
@property(nullable, nonatomic,strong) UIImage *selectedImage NS_AVAILABLE_IOS(7_0);
//角標
@property(nullable, nonatomic, copy) NSString *badgeValue;
//IOS7以后過期
- (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以后過期
- (nullable UIImage *)finishedSelectedImage NS_DEPRECATED_IOS(5_0,7_0);
//IOS7以后過期
- (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
知識點1：tabBarItem相關屬性運用
1) 用來控制一組控制器的切換，類似選項卡，每個Tab控制一個試圖控制器，點擊哪個tab就顯示對應的試圖控制器，當前的試圖控制器
2) 每個tabBarItem都可以設置title、image/selectedImages、badgeValue
例如：
（1）.給當前的分欄控制器的item設置一個標題
self.tabBarItem.title = @"我的";
（2）.給當前的分欄控制器的item設置一個圖片
self.tabBarItem.image = [UIImage imageNamed:@"tab_buddy_nor@2x"];
（3）.給當前的分欄控制器的item設置一個選中狀態(tài)的圖片
self.tabBarItem.selectedImage = [UIImage imageNamed:@"tab_me_nor@2x"];//@2x表示給高清屏 30*30的效果好
self.tabBarItem.badgeValue = @"new";//在小圖標的上面家字體加字體
3) 設置選中的顏色
分欄控制器.tabBar.tintColor
self.tabBarController.tabBar.tintColor = [UIColor redColor];
3) TabBar只能顯示五個tab Item，如果超過五個則會自動生成個Morede 標簽顯示剩余的Tab,這些Tab可以通過編輯顯示在UITabBar上（打開頁面后自動顯示在界面，點擊tabBar右邊）
4) 自定義Item
[UITabBarItem alloc]initWithTitle: image: tag:
[UITabBarItem alloc]initWithTabBarSystemItem:tag:
