[UIButton+BadgeValue]—UIButton's Category to enable UIButton to set badgeValue like UITabBarItem.

UIButton+BadgeValue.h

#import <UIKit/UIKit.h>

@interface UIButton (BadgeValue)

- (void)setBadgeValue:(NSString *)value;

@end

UIButton+BadgeValue.m

#import "UIButton+BadgeValue.h"

@implementation UIButton (BadgeValue)

- (void)setBadgeValue:(NSString *)value
{
    static UILabel *lb_badgeValue = nil;
    if (value) {
        if (!lb_badgeValue) {
            lb_badgeValue = [[UILabel alloc] initWithFrame:CGRectMake(self.frame.size.width/2, 0, self.frame.size.width/2, self.frame.size.height/2)];
            lb_badgeValue.textAlignment = NSTextAlignmentCenter;
            lb_badgeValue.textColor = [UIColor whiteColor];
            lb_badgeValue.backgroundColor = [UIColor redColor];
            lb_badgeValue.layer.masksToBounds = YES;
            lb_badgeValue.layer.cornerRadius = self.frame.size.width/4;
            [self addSubview:lb_badgeValue];
        }
        NSInteger frontSize = 14;
        NSInteger length = [value length];
        switch (length) {
            case 1:
                frontSize = 14;
                break;
            case 2:
                frontSize = 12;
                break;
            case 3:
                frontSize = 8;
                break;
            default:
                frontSize = 10;
                break;
        }
        lb_badgeValue.font = [UIFont systemFontOfSize:frontSize];
        lb_badgeValue.text = value;
    }else{
        if (lb_badgeValue) {
            [lb_badgeValue removeFromSuperview];
            lb_badgeValue = nil;
        }
    }
}

@end