如上圖這種點選TabBar中間Button時present（模態）出控制器，而點選TabBar其它的Button則是蘋果預設的直接切換檢視的方式，現在很多APP都在使用，特別是直播APP，基本都把直播端模組放在這，最近在仿喵播時正好做到這，就想在網上找現成的框架，結果一直沒找到能滿足這種需求的框架，就自己動手寫了一個，沒有仔細打磨算不上框架，但絕對簡單好用！

自定義TabBarController實現原理很簡單，無非是用自定義的Button替換掉蘋果自帶的TabBar上的Button，一般目的是想TabBar上方顯示按鈕圖片，下面是文字；也就是每個Button下面有一個Label

1、 新建三個類：

• JFTabBar繼承自UIview
• JFTabBarButton繼承自UIButton
• JFTabBarController繼承自UITabBarController

2、具體程式碼：

• JFTabBar.h

#import <UIKit/UIKit.h>

@class JFTabBar;

@protocol JFTabBarDelegate <NSObject>

@optional

- (void)tabBar:(JFTabBar *)tabBar didSelectedButtonFrom:(int
 
)from to:(int)to;

@end

@interface JFTabBar : UIView

- (void)addTabBarButtonWithItem:(UITabBarItem *)item;

- (void)customTheMiddleButtonWithImageName:(NSString *)imageName;

@property (nonatomic, weak) id<JFTabBarDelegate> delegate;

@end

• JFTabBar.m

#import "JFTabBar.h"

#import "JFTabBarButton.h"
 


//中間按鈕被點選的通知
//此通知需要在JFTabBarController中監聽
static NSString * const JFTabBarClickMiddleButtonDidNotification = @"JFTabBarClickMiddleButtonDidNotification";

@interface JFTabBar(){
    CGFloat _buttonW;
}

@property (nonatomic, weak) JFTabBarButton *selectedButton;

@property (nonatomic, strong) UIButton *middleButton;

@end

@implementation JFTabBar

- (void)addTabBarButtonWithItem:(UITabBarItem *)item {
    JFTabBarButton *button = [[JFTabBarButton alloc] init];
    [self addSubview:button];
    button.item = item;
    [button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchDown];
    if (self.subviews.count == 1) {
        [self buttonClick:button];
    }
}

- (void)buttonClick:(JFTabBarButton *)button {
    if ([self.delegate respondsToSelector:@selector(tabBar:didSelectedButtonFrom:to:)]) {
        [self.delegate tabBar:self didSelectedButtonFrom:(int)self.selectedButton.tag to:(int)button.tag];
    }
    self.selectedButton.selected = NO;
    button.selected = YES;
    self.selectedButton = button;
}

/**
 *  self.subviews.count + 1 這裡加1是將button的width按三個button計算，實際上是兩個button（如果不想present就不需要加1，下面兩個if判斷也可以去掉）
 *  兩個if判斷：1、是將button的x座標按三個button計算；2、tag值迴歸正常，不然無法正常切換控制器
 *  如你需要新增更多的控制器，這裡就需要你自己計算，然後修改以上兩點
 */
- (void)layoutSubviews {
    [super layoutSubviews];
    CGFloat buttonH = self.frame.size.height;
    _buttonW = self.frame.size.width / (self.subviews.count + 1);
    CGFloat buttonY = 0;
    for (int index = 0; index < self.subviews.count; index++) {
        JFTabBarButton *button = self.subviews[index];
        if (index == 1) index ++;
        CGFloat buttonX = index * _buttonW;
        button.frame = CGRectMake(buttonX, buttonY, _buttonW, buttonH);
        if (index == 2) index --;
        button.tag = index;
    }
    [self customTheMiddleButtonWithImageName:@"toolbar_live"];
}

//自定義中間button按鈕
- (void)customTheMiddleButtonWithImageName:(NSString *)imageName {
//  將Button居中
    CGFloat middleButtonX = self.center.x - _buttonW / 2;
    _middleButton = [[UIButton alloc] initWithFrame:CGRectMake(middleButtonX, 0, _buttonW, self.frame.size.height)];
    [_middleButton setImage:[UIImage imageNamed:imageName] forState:UIControlStateNormal];
    [_middleButton addTarget:self action:@selector(didClickedMiddleButton:) forControlEvents:UIControlEventTouchDown];
    [self addSubview:_middleButton];
}

- (void)didClickedMiddleButton:(UIButton *)sender {
    //註冊中間button被點選通知
    [[NSNotificationCenter defaultCenter] postNotificationName:JFTabBarClickMiddleButtonDidNotification object:self];
}
@end

• JFTabBarButton.h

#import <UIKit/UIKit.h>

@interface JFTabBarButton : UIButton

@property (nonatomic, strong) UITabBarItem *item;

@end

• JFTabBarButton.m

static const double JFTabBarButtonImageRatio = 0.8;
#import "JFTabBarButton.h"

@implementation JFTabBarButton

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.imageView.contentMode = UIViewContentModeCenter;
        self.titleLabel.textAlignment = NSTextAlignmentCenter;
        self.titleLabel.font = [UIFont systemFontOfSize:11];
        [self setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
    }
    return self;
}

- (void)setHighlighted:(BOOL)highlighted {}

- (CGRect)imageRectForContentRect:(CGRect)contentRect{
    CGFloat imageW = contentRect.size.width;
    CGFloat imageH = contentRect.size.height * JFTabBarButtonImageRatio;
    return CGRectMake(0, 10, imageW, imageH);
}

//Button下需要文字時開啟
//- (CGRect)titleRectForContentRect:(CGRect)contentRect {
//    CGFloat titleY = contentRect.size.height * JFTabBarButtonImageRatio;
//    CGFloat titleW = contentRect.size.width;
//    CGFloat titleH = contentRect.size.height - titleY;
//    return CGRectMake(0, titleY, titleW, titleH);
//}

- (void)setItem:(UITabBarItem *)item {
    _item = item;
    //Button下需要文字時開啟
//    [item addObserver:self forKeyPath:@"title" options:0 context:nil];
    [item addObserver:self forKeyPath:@"image" options:0 context:nil];
    [item addObserver:self forKeyPath:@"selectedImage" options:0 context:nil];

    [self observeValueForKeyPath:nil ofObject:nil change:nil context:nil];
}

- (void)dealloc {
    //Button下需要文字時開啟
//    [self.item removeObserver:self forKeyPath:@"title"];
    [self.item removeObserver:self forKeyPath:@"image"];
    [self.item removeObserver:self forKeyPath:@"selectedImage"];
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
//    [self setTitle:self.item.title forState:UIControlStateSelected];
//    [self setTitle:self.item.title forState:UIControlStateNormal];
    [self setImage:self.item.image forState:UIControlStateNormal];
    [self setImage:self.item.selectedImage forState:UIControlStateSelected];
}

@end

• JFTabBarController.h

在- (void)addAllChildViewControllers中新增除中間那個你需要present（模態）出的控制器

#import <UIKit/UIKit.h>

extern NSString * const JFTabBarClickMiddleButtonDidNotification;

@interface JFTabBarController : UITabBarController

@end

• JFTabBarController.m

#import "JFTabBarController.h"

#import "JFTabBar.h"
#import "JFDisplayViewController.h"
#import "JFMeViewController.h"
#import "JFLiveViewController.h"

@interface JFTabBarController ()<JFTabBarDelegate>

@property (nonatomic, weak) JFTabBar *customTabBar;

@end

@implementation JFTabBarController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self customTabBarUI];
//  新增子控制器
    [self addAllChildViewControllers];

//  監聽中間按鈕點選事件
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(presentLiveController) name:@"JFTabBarClickMiddleButtonDidNotification" object:nil];
}
//  移除原生的TabBar
- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    for (UIView *childView in self.tabBar.subviews) {
        if ([childView isKindOfClass:[UIControl class]]) {
            [childView removeFromSuperview];
        }
    }
}

- (void)customTabBarUI {
    JFTabBar *customTabBar = [[JFTabBar alloc] init];
    customTabBar.frame = self.tabBar.bounds;
    customTabBar.delegate = self;
    [self.tabBar addSubview:customTabBar];
    self.customTabBar = customTabBar;
}

- (void)tabBar:(JFTabBar *)tabBar didSelectedButtonFrom:(int)from to:(int)to{
    self.selectedIndex = to;
}

//   下面換成你自己需要新增的控制器就好,只新增除中間需要present（模態）出的控制器。
- (void)addAllChildViewControllers {
    JFDisplayViewController *displayVC = [[JFDisplayViewController alloc] init];
    [self addChildViewController:displayVC title:@"視訊" imageName:@"toolbar_home" selectedImageName:@"toolbar_home_sel"];
    JFMeViewController *meVC = [[JFMeViewController alloc] init];
    [self addChildViewController:meVC title:@"個人" imageName:@"toolbar_me" selectedImageName:@"toolbar_me_sel"];
}

- (void)addChildViewController:(UIViewController *)childViewController title:(NSString *)title imageName:(NSString *)imageName selectedImageName:(NSString *)selectedImageName {
    childViewController.title = title;
    childViewController.tabBarItem.image = [UIImage imageNamed:imageName];
    childViewController.tabBarItem.selectedImage = [[UIImage imageNamed:selectedImageName] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:childViewController];
    [self addChildViewController:navigationController];
    [self.customTabBar addTabBarButtonWithItem:childViewController.tabBarItem];
}

//接收到點選中間按鈕的通知，present（模態）出控制器
- (void)presentLiveController {
    JFLiveViewController *jfLiveVC = [[JFLiveViewController alloc] init];
    [self presentViewController:jfLiveVC animated:YES completion:nil];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

//  移除通知
- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}
@end

說了這麼多，如果你也只是需要三個控制器，其實你只需要做這些：
1、下載JFTabBarController原始碼，解壓將JFTabBarController資料夾中檔案直接拖入你的xcode專案工程中。
2、在AppDelegate.m檔案中JFTabBarController設為window的根控制器。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    self.window.backgroundColor = [UIColor whiteColor];
    self.window.rootViewController = [[JFTabBarController alloc] init];
    [self.window makeKeyAndVisible];
    return YES;
}

3、重寫JFTabBarcontroller.m檔案中-(void)addAllChildViewControllers函式，新增子控制器
4、JFTabBarClickMiddleButtonDidNotification通知，
重寫JFTabBarcontroller.m檔案中- (void)presentLiveController方法。
你需要做的就這四步！