#import <UIKit/UIKit.h>

@class DJTabBar;

@protocol DJTabBarDelegate <UITabBarDelegate>

@optional

- (void)tabBarDidClickPlusBtn:(DJTabBar *)tabBar;

@end

@interface DJTabBar : UITabBar

+ (instancetype)tabBar;

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

@end

#import "DJTabBar.h"

@interface DJTabBar()

@property (nonatomic,weak) UIButton *plusBtn;

@end

@implementation DJTabBar

@dynamic delegate;

- (UIButton *)plusBtn {

    if (!_plusBtn) {

        UIButton *plusBtn = [[UIButton alloc] init];

        [plusBtn setBackgroundImage:[UIImage imageNamed:@"tabbar_compose_button"] forState:UIControlStateNormal];

        [plusBtn setBackgroundImage:[UIImage imageNamed:@"tabbar_compose_button_highlighted"] forState:UIControlStateHighlighted];

        [plusBtn setImage:[UIImage imageNamed:@"tabbar_compose_icon_add"] forState:UIControlStateNormal];

        [plusBtn setImage:[UIImage imageNamed:@"tabbar_compose_icon_add_highlighted"] forState:UIControlStateHighlighted];

        plusBtn.size = plusBtn.currentBackgroundImage.size;

        [self addSubview:plusBtn];

        _plusBtn = plusBtn;

    }

    return _plusBtn;

}

+ (instancetype)tabBar {

    return [[self alloc] init];

}

- (instancetype)initWithFrame:(CGRect)frame {

    if (self = [super initWithFrame:frame]) {

        [self.plusBtn addTarget:self action:@selector(plusBtnClick) forControlEvents:UIControlEventTouchUpInside];

    }

    return self;

}

- (void)layoutSubviews {

    [super layoutSubviews];

    // 设置plusBtn的位置

    self.plusBtn.centerX = self.width * 0.5;

    self.plusBtn.centerY = self.height *0.5;

    // 设置tabBa上面四个UIBarButton的位置

    Class clazz = NSClassFromString(@"UITabBarButton");

    NSUInteger currentChildIndex = ;

    NSUInteger childWidth = self.width / ;

    for (UIView *childView in self.subviews) {

        if ([childView isKindOfClass:clazz]) {

            // 如果是第三个tabBar,则自动跳转到第四个

            if (currentChildIndex == ) {

                currentChildIndex++;

            }

            // 调整位置及大小

            childView.width = childWidth;

            childView.x = childWidth * currentChildIndex;

//            childView.backgroundColor = [UIColor redColor];

            currentChildIndex++;

        }

    }

}

- (void)plusBtnClick {

    DJLog(@"click.......");

    if ([self.delegate respondsToSelector:@selector(tabBarDidClickPlusBtn:)]) {

        [self.delegate tabBarDidClickPlusBtn:self];

    }

}

@end

// 2.添加发送微博按钮

    DJTabBar *tabBar = [DJTabBar tabBar];

    tabBar.delegate = self;

    [self setValue:tabBar forKey:@"tabBar"];