最終效果：

思路是
1.移除原來的tabbar,自定義一個view
2.覆蓋原來的tabbar

======華麗的分割線====
演示覆蓋
1.拉一個Tab bar Controller進storyboard

圖1

2.command + N創建文件繼承自UITarbarController
3.command + N在創建繼承自UIView
如下圖所示

我就是如下圖

4.在Controller中加入view,並且加入UIButton

<code>#import "PLTabBarController.h"
#import "TabBarView.h"

@interface PLTabBarController ()&lt;TabBarViewDelegate&gt;


@end

@implementation PLTabBarController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    TabBarView * tabbar = [[TabBarView alloc]init];
    tabbar.frame = self.tabBar.bounds;
    tabbar.delegate = self;

    NSString * imageName = nil;
    NSString * selName = nil;
    for (int i = 0; i &lt; self.childViewControllers.count; i++) {
        imageName = [NSString stringWithFormat:@"%d",i+1];
        selName = [NSString stringWithFormat:@"s%d",i+1];
        [tabbar addTarBarButtonWithName:imageName selName:selName];
    }
    [self.tabBar addSubview:tabbar];

}

- (void)tabbar:(TabBarView *)tabbar didSelectedIndex:(NSInteger)selectIndex
{
    self.selectedIndex = selectIndex;
}


@end</code>

5.UIButton實現點擊效果，代理切換控制器
.h文件

<code>#import &lt;UIKit/UIKit.h&gt;

@class TabBarView;

@protocol TabBarViewDelegate&lt;NSObject&gt;

@optional
- (void)tabbar:(TabBarView*)tabbar didSelectedIndex:(NSInteger)selectIndex;

@end

@interface TabBarView : UIView

@property (nonatomic, weak) id &lt;TabBarViewDelegate&gt; delegate;

- (void)addTarBarButtonWithName:(NSString *)name selName:(NSString *)selName;

@end</code>

.m

<code>#import "TabBarView.h"

@interface TabBarView ()

@property (nonatomic, weak) UIButton *selectedBtn;

@end

@implementation TabBarView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {

    }
    return self;
}

- (void)addTarBarButtonWithName:(NSString *)name selName:(NSString *)selName
{
    UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
     forState:UIControlStateNormal];
     forState:UIControlStateSelected];
    ;
    [self addSubview:button];
}

- (void)btnClicked:(UIButton *)button
{
    self.selectedBtn.selected = NO;
    button.selected = YES;
    self.selectedBtn = button;

    if ([self.delegate respondsToSelector:@selector(tabbar:didSelectedIndex:)]) {
        [self.delegate tabbar:self didSelectedIndex:button.tag];
    }
}

- (void)layoutSubviews
{
    [super layoutSubviews];

    CGFloat btnX = 0;
    CGFloat btnY = 0;
    CGFloat btnW = self.frame.size.width /self.subviews.count;
    CGFloat btnH = self.frame.size.height;

    for (int i = 0; i &lt; self.subviews.count; i++) {
        UIButton * btn =  self.subviews[i];
        btn.tag = i;
        btnX = i * btnW;
        [btn setFrame:CGRectMake(btnX, btnY, btnW, btnH)];
        if (i == 0) {
            [self btnClicked:btn];
        }
    }
}

@end</code>