不废话，直接上代码！

//新标识视图
self.badgeView = [[JSBadgeView alloc]initWithParentView:parentView alignment:JSBadgeViewAlignmentTopRight];  //在父控件（parentView）上显示，显示的位置TopRight
  //self.badgeView.badgePositionAdjustment = CGPointMake(-15, 10);  //如果显示的位置不对，可以自己调整，超爽啊！
self.badgeView.tag = IN_AREA_NEW_TASKS_TAG; //如果多个的badge,可以设置tag要辨别
/****如果系统是7.0以上，图标扁平化,可以设置颜色****/
if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"7.0"))
{
    self.badgeView.badgeBackgroundColor = [UIColor redColor];
    self.badgeView.badgeOverlayColor = [UIColor clearColor];//没有反光面
    self.badgeView.badgeStrokeColor = [UIColor redColor];//外圈的颜色，默认是白色
}
else //如果iOS版本小于7.0，用类似系统的图标
{
    self.badgeView1.badgeBackgroundColor = [UIColor redColor];

}

/*****设置数字****/
self.badgeView.badgeText = @"1";//如果不显示就</span>设置为空
self.badgeView.badgeText = nil; //清空数字

[self.badgeView setNeedsLayout];//当更新数字时，最好刷新，不然由于frame固定的，导致图片变形

原JSBadgeView（修改过，适配iOS7、8的扁平化）的代码

/*
 Copyright 2012 Javier Soto ([email protected])
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
 http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import <UIKit/UIKit.h>

typedef enum {
    JSBadgeViewAlignmentTopLeft,
    JSBadgeViewAlignmentTopRight,
    JSBadgeViewAlignmentTopCenter,
    JSBadgeViewAlignmentCenterLeft,
    JSBadgeViewAlignmentCenterRight,
    JSBadgeViewAlignmentBottomLeft,
    JSBadgeViewAlignmentBottomRight,
    JSBadgeViewAlignmentBottomCenter,
    JSBadgeViewAlignmentCenter
} JSBadgeViewAlignment;

@interface JSBadgeView : UIView

@property (nonatomic, copy) NSString *badgeText;

#pragma mark - Customization

@property (nonatomic, assign) JSBadgeViewAlignment badgeAlignment;

@property (nonatomic, strong) UIColor *badgeTextColor;
@property (nonatomic, assign) CGSize badgeTextShadowOffset;
@property (nonatomic, strong) UIColor *badgeTextShadowColor;

@property (nonatomic, strong) UIFont *badgeTextFont;

@property (nonatomic, strong) UIColor *badgeBackgroundColor;

@property (nonatomic, strong) UIColor *badgeStrokeColor;

/**
 * @discussion color of the overlay circle at the top. Default is semi-transparent white.
 */
@property (nonatomic, strong) UIColor *badgeOverlayColor;

/**
 * @discussion allows to shift the badge by x and y points.
 */
@property (nonatomic, assign) CGPoint badgePositionAdjustment;

/**
 * @discussion (optional) If not provided, the superview frame is used.
 * You can use this to position the view if you're drawing it using drawRect instead of `-addSubview:`
 */
@property (nonatomic, assign) CGRect frameToPositionInRelationWith;

/**
 * @discussion optionally init using this method to have the badge automatically added to another view.
 */
- (id)initWithParentView:(UIView *)parentView alignment:(JSBadgeViewAlignment)alignment;

@end

/*
 Copyright 2012 Javier Soto ([email protected])
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
 http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import "JSBadgeView.h"

#import <QuartzCore/QuartzCore.h>

#define kDefaultBadgeTextColor [UIColor whiteColor]
#define kDefaultBadgeBackgroundColor [UIColor redColor]
#define kDefaultOverlayColor [UIColor colorWithWhite:1.0f alpha:0.3]

#define kDefaultBadgeTextFont [UIFont boldSystemFontOfSize:[UIFont systemFontSize]]

#define kDefaultBadgeShadowColor [UIColor clearColor]

#define kBadgeStrokeColor [UIColor whiteColor]
#define kBadgeStrokeWidth 2.0f

#define kMarginToDrawInside (kBadgeStrokeWidth * 2)

#define kShadowOffset CGSizeMake(0.0f, 3.0f)
#define kShadowOpacity 0.4f
#define kShadowColor [UIColor colorWithWhite:0.0f alpha:kShadowOpacity]
#define kShadowRadius 1.0f

#define kBadgeHeight 16.0f
#define kBadgeTextSideMargin 8.0f

#define kBadgeCornerRadius 10.0f

#define kDefaultBadgeAlignment JSBadgeViewAlignmentTopRight

@interface JSBadgeView()

- (void)_init;
- (CGSize)sizeOfTextForCurrentSettings;

@end

@implementation JSBadgeView

@synthesize badgeAlignment = _badgeAlignment;

@synthesize badgePositionAdjustment = _badgePositionAdjustment;
@synthesize frameToPositionInRelationWith = _frameToPositionInRelationWith;

@synthesize badgeText = _badgeText;
@synthesize badgeTextColor = _badgeTextColor;
@synthesize badgeTextShadowColor = _badgeTextShadowColor;
@synthesize badgeTextShadowOffset = _badgeTextShadowOffset;
@synthesize badgeTextFont = _badgeTextFont;
@synthesize badgeBackgroundColor = _badgeBackgroundColor;
@synthesize badgeOverlayColor = _badgeOverlayColor;
@synthesize badgeStrokeColor = _badgeStrokeColor;

- (void)awakeFromNib
{
    [super awakeFromNib];

    [self _init];
}

- (id)initWithFrame:(CGRect)frame
{
    if ((self = [super initWithFrame:frame]))
    {
        [self _init];
    }

    return self;
}

- (id)initWithParentView:(UIView *)parentView alignment:(JSBadgeViewAlignment)alignment
{
    if ((self = [self initWithFrame:CGRectZero]))
    {
        self.badgeAlignment = alignment;
        [parentView addSubview:self];
    }
    
    return self;
}

- (void)_init
{    
    self.backgroundColor = [UIColor clearColor];
    
    self.badgeAlignment = kDefaultBadgeAlignment;
    
    self.badgeBackgroundColor = kDefaultBadgeBackgroundColor;
    self.badgeOverlayColor = kDefaultOverlayColor;
    self.badgeTextColor = kDefaultBadgeTextColor;
    self.badgeStrokeColor = kBadgeStrokeColor;
    self.badgeTextShadowColor = kDefaultBadgeShadowColor;
    self.badgeTextFont = kDefaultBadgeTextFont;
}

#pragma mark - Layout

- (void)layoutSubviews
{    
    CGRect newFrame = self.frame;
    NSLog(@"badge frame:%@",NSStringFromCGRect(newFrame));
    CGRect superviewFrame = CGRectIsEmpty(_frameToPositionInRelationWith) ? self.superview.frame : _frameToPositionInRelationWith;
    
    CGFloat textWidth = [self sizeOfTextForCurrentSettings].width;
    
    CGFloat viewWidth = textWidth + kBadgeTextSideMargin + (kMarginToDrawInside * 2);
    CGFloat viewHeight = kBadgeHeight + (kMarginToDrawInside * 2);
    
    CGFloat superviewWidth = superviewFrame.size.width;
    CGFloat superviewHeight = superviewFrame.size.height;
    
    newFrame.size.width = viewWidth;
    newFrame.size.height = viewHeight;
    
    switch (self.badgeAlignment) {
        case JSBadgeViewAlignmentTopLeft:
            newFrame.origin.x = -viewWidth / 2.0f;
            newFrame.origin.y = -viewHeight / 2.0f;
            break;
        case JSBadgeViewAlignmentTopRight:
            newFrame.origin.x = superviewWidth - (viewWidth / 2.0f);
            newFrame.origin.y = -viewHeight / 2.0f;
            break;
        case JSBadgeViewAlignmentTopCenter:
            newFrame.origin.x = (superviewWidth - viewWidth) / 2.0f;
            newFrame.origin.y = -viewHeight / 2.0f;
            break;
        case JSBadgeViewAlignmentCenterLeft:
            newFrame.origin.x = -viewWidth / 2.0f;
            newFrame.origin.y = (superviewHeight - viewHeight) / 2.0f;
            break;
        case JSBadgeViewAlignmentCenterRight:
            newFrame.origin.x = superviewWidth - (viewWidth / 2.0f);
            newFrame.origin.y = (superviewHeight - viewHeight) / 2.0f;
            break;
        case JSBadgeViewAlignmentBottomLeft:
            newFrame.origin.x = -textWidth / 2.0f;
            newFrame.origin.y = superviewHeight - (viewHeight / 2.0f);
            break;
        case JSBadgeViewAlignmentBottomRight:
            newFrame.origin.x = superviewWidth - (viewWidth / 2.0f);
            newFrame.origin.y = superviewHeight - (viewHeight / 2.0f);
            break;
        case JSBadgeViewAlignmentBottomCenter:
            newFrame.origin.x = (superviewWidth - viewWidth) / 2.0f;
            newFrame.origin.y = superviewHeight - (viewHeight / 2.0f);
            break;
        case JSBadgeViewAlignmentCenter:
            newFrame.origin.x = (superviewWidth - viewWidth) / 2.0f;
            newFrame.origin.y = (superviewHeight - viewHeight) / 2.0f;
            break;
        default:
            NSAssert(NO, @"Unimplemented JSBadgeAligment type %d", self.badgeAlignment);
    }
    
    newFrame.origin.x += _badgePositionAdjustment.x;
    newFrame.origin.y += _badgePositionAdjustment.y;
    
    self.frame = CGRectIntegral(newFrame);
    
    [self setNeedsDisplay];
}

#pragma mark - Private

- (CGSize)sizeOfTextForCurrentSettings
{
    return [self.badgeText sizeWithFont:self.badgeTextFont];
}

#pragma mark - Setters

- (void)setBadgeAlignment:(JSBadgeViewAlignment)badgeAlignment
{
    if (badgeAlignment != _badgeAlignment)
    {
        _badgeAlignment = badgeAlignment;

        switch (badgeAlignment)
        {
            case JSBadgeViewAlignmentTopLeft:
                self.autoresizingMask = UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleRightMargin;
                break;
            case JSBadgeViewAlignmentTopRight:
                self.autoresizingMask = UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin;
                break;
            case JSBadgeViewAlignmentTopCenter:
                self.autoresizingMask = UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin;
                break;
            case JSBadgeViewAlignmentCenterLeft:
                self.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleRightMargin;
                break;
            case JSBadgeViewAlignmentCenterRight:
                self.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleLeftMargin;
                break;
            case JSBadgeViewAlignmentBottomLeft:
                self.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleRightMargin;
                break;
            case JSBadgeViewAlignmentBottomRight:
                self.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleLeftMargin;
                break;
            case JSBadgeViewAlignmentBottomCenter:
                self.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin;
                break;
            case JSBadgeViewAlignmentCenter:
                self.autoresizingMask = UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleBottomMargin;
                break;
            default:
                NSAssert(NO, @"Unimplemented JSBadgeAligment type %d", self.badgeAlignment);
        }

        [self setNeedsLayout];
    }
}

- (void)setBadgePositionAdjustment:(CGPoint)badgePositionAdjustment
{
    _badgePositionAdjustment = badgePositionAdjustment;
    
    [self setNeedsLayout];
}

- (void)setBadgeText:(NSString *)badgeText
{
    if (badgeText != _badgeText)
    {
        _badgeText = [badgeText copy];
        
        [self setNeedsDisplay];
    }
}

- (void)setBadgeTextColor:(UIColor *)badgeTextColor
{
    if (badgeTextColor != _badgeTextColor)
    {
        _badgeTextColor = badgeTextColor;
        
        [self setNeedsDisplay];
    }
}

- (void)setBadgeTextShadowColor:(UIColor *)badgeTextShadowColor
{
    if (badgeTextShadowColor != _badgeTextShadowColor)
    {
        _badgeTextShadowColor = badgeTextShadowColor;
        
        [self setNeedsDisplay];
    }
}

- (void)setBadgeTextShadowOffset:(CGSize)badgeTextShadowOffset
{
    _badgeTextShadowOffset = badgeTextShadowOffset;
    
    [self setNeedsDisplay];
}

- (void)setBadgeTextFont:(UIFont *)badgeTextFont
{
    if (badgeTextFont != _badgeTextFont)
    {
        _badgeTextFont = badgeTextFont;
        
        [self setNeedsDisplay];
    }
}

- (void)setBadgeBackgroundColor:(UIColor *)badgeBackgroundColor
{
    if (badgeBackgroundColor != _badgeBackgroundColor)
    {
        _badgeBackgroundColor = badgeBackgroundColor;
        
        [self setNeedsDisplay];
    }
}

-(void)setBadgeStrokeColor:(UIColor *)badgeStrokeColor
{
    if (badgeStrokeColor != _badgeStrokeColor)
    {
        _badgeStrokeColor = badgeStrokeColor;
        
        [self setNeedsDisplay];
    }
}

#pragma mark - Drawing

- (void)drawRect:(CGRect)rect
{
    BOOL anyTextToDraw = (self.badgeText.length > 0);
    
    if (anyTextToDraw)
    {
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        
        CGRect rectToDraw = CGRectInset(rect, kMarginToDrawInside, kMarginToDrawInside);
        
        UIBezierPath *borderPath = [UIBezierPath bezierPathWithRoundedRect:rectToDraw byRoundingCorners:(UIRectCorner)UIRectCornerAllCorners cornerRadii:CGSizeMake(kBadgeCornerRadius, kBadgeCornerRadius)];
        
        /* Background and shadow */
        CGContextSaveGState(ctx);
        {
            CGContextAddPath(ctx, borderPath.CGPath);
            
            CGContextSetFillColorWithColor(ctx, self.badgeBackgroundColor.CGColor);
            CGContextSetShadowWithColor(ctx, kShadowOffset, kShadowRadius, kShadowColor.CGColor);
            
            CGContextDrawPath(ctx, kCGPathFill);
        }
        CGContextRestoreGState(ctx);
        
        BOOL colorForOverlayPresent = self.badgeOverlayColor && ![self.badgeOverlayColor isEqual:[UIColor clearColor]];
        
        if (colorForOverlayPresent)
        {
            /* Gradient overlay */
            CGContextSaveGState(ctx);
            {
                CGContextAddPath(ctx, borderPath.CGPath);
                CGContextClip(ctx);
                
                CGFloat height = rectToDraw.size.height;
                CGFloat width = rectToDraw.size.width;
                
                CGRect rectForOverlayCircle = CGRectMake(rectToDraw.origin.x,
                                                         rectToDraw.origin.y - ceilf(height * 0.5),
                                                         width,
                                                         height);
                
                CGContextAddEllipseInRect(ctx, rectForOverlayCircle);
                CGContextSetFillColorWithColor(ctx, self.badgeOverlayColor.CGColor);
                
                CGContextDrawPath(ctx, kCGPathFill);
            }
            CGContextRestoreGState(ctx);
        }
        
        /* Stroke */
        CGContextSaveGState(ctx);
        {
            CGContextAddPath(ctx, borderPath.CGPath);
            
            CGContextSetLineWidth(ctx, kBadgeStrokeWidth);
            CGContextSetStrokeColorWithColor(ctx, self.badgeStrokeColor.CGColor);
            
            CGContextDrawPath(ctx, kCGPathStroke);
        }
        CGContextRestoreGState(ctx);
        
        /* Text */
        CGContextSaveGState(ctx);
        {
            CGContextSetFillColorWithColor(ctx, self.badgeTextColor.CGColor);
            CGContextSetShadowWithColor(ctx, self.badgeTextShadowOffset, 1.0, self.badgeTextShadowColor.CGColor);
            
            CGRect textFrame = rectToDraw;
            CGSize textSize = [self sizeOfTextForCurrentSettings];
            
            textFrame.size.height = textSize.height;
            textFrame.origin.y = rectToDraw.origin.y + ceilf((rectToDraw.size.height - textFrame.size.height) / 2.0f);
            
            [self.badgeText drawInRect:textFrame
                              withFont:self.badgeTextFont
                         lineBreakMode:NSLineBreakByCharWrapping
                             alignment:NSTextAlignmentCenter];
        }
        CGContextRestoreGState(ctx);
    }
}

@end

nice~