2019-04-07给TabBar添加未读消息小红点儿

第一步，建一个UITabBar的category类别

第二步：上代码

#import <UIKit/UIKit.h>

@interface UITabBar (badge)

- (void)showBadgeOnItemIndex:(int)index;   //显示小红点

- (void)hideBadgeOnItemIndex:(int)index; //隐藏小红点

@end

#import "UITabBar+badge.h"
#define TabbarItemNums 4.0    //tabbar的数量

@implementation UITabBar (badge)
- (void)showBadgeOnItemIndex:(int)index{  

    //移除之前的小红点
    [self removeBadgeOnItemIndex:index];

    //新建小红点
    UIView *badgeView = [[UIView alloc]init];
    badgeView.tag = 888 + index;
    badgeView.layer.cornerRadius = 5;
    badgeView.backgroundColor = [UIColor redColor];
    CGRect tabFrame = self.frame;

    //确定小红点的位置
    float percentX = (index +0.6) / TabbarItemNums;
    CGFloat x = ceilf(percentX * tabFrame.size.width);
    CGFloat y = ceilf(0.1 * tabFrame.size.height);
    badgeView.frame = CGRectMake(x, y, 10, 10);
    [self addSubview:badgeView];

}

- (void)hideBadgeOnItemIndex:(int)index{

    //移除小红点
    [self removeBadgeOnItemIndex:index];

}

- (void)removeBadgeOnItemIndex:(int)index{

    //按照tag值进行移除
    for (UIView *subView in self.subviews) {

        if (subView.tag == 888+index) {

            [subView removeFromSuperview];

        }
    }
}

@end

第三步，在需要用到的地方使用

//显示
[self.tabBarController.tabBar showBadgeOnItemIndex:2];

//隐藏
[self.tabBarController.tabBar hideBadgeOnItemIndex:2]