如何在iPhone 显示一个 星级评分

由于项目需求，需要做一个列表，里面有各个商品的评分，就是app store里面所有app的星级评分

下面是DisplayStarView.h

//
//  DisplayStarView.h
//  testExpress
//
//  Created by Juncy_Fan on 13-3-12.
//  Copyright (c) 2013年 Juncy_Fan. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface DisplayStarView : UIView
{
    CGFloat _starSize;        /* 根据字体大小来确定星星的大小 */
    NSInteger _maxStar;      /* 总共的长度 */
    NSInteger _showStar;    //需要显示的星星的长度
    UIColor *_emptyColor;   //未点亮时候的颜色
    UIColor *_fullColor;    //点亮的星星的颜色
}
@property (nonatomic, assign) CGFloat starSize;
@property (nonatomic, assign) NSInteger maxStar;
@property (nonatomic, assign) NSInteger showStar;
@property (nonatomic, retain) UIColor *emptyColor;
@property (nonatomic, retain) UIColor *fullColor;
@end

DisplayStarView.m如下

//
//  DisplayStarView.m
//  testExpress
//
//  Created by Juncy_Fan on 13-3-12.
//  Copyright (c) 2013年 Juncy_Fan. All rights reserved.
//

#import "DisplayStarView.h"

@implementation DisplayStarView
@synthesize starSize = _starSize;
@synthesize maxStar = _maxStar;
@synthesize showStar = _showStar;
@synthesize emptyColor = _emptyColor;
@synthesize fullColor = _fullColor;

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self)
    {
        self.backgroundColor = [UIColor clearColor];
        //默认的星星的大小是 13.0f
        self.starSize = 13.0f;
        //未点亮时的颜色是 灰色的
        self.emptyColor = [UIColor colorWithRed:167.0f / 255.0f green:167.0f / 255.0f blue:167.0f / 255.0f alpha:1.0f];
        //点亮时的颜色是 亮黄色的
        self.fullColor = [UIColor colorWithRed:255.0f / 255.0f green:121.0f / 255.0f blue:22.0f / 255.0f alpha:1.0f];
        //默认的长度设置为100
        self.maxStar = 100;
    }
    
    return self;
}

//重绘视图
- (void)drawRect:(CGRect)rect
{
    // Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    NSString* stars = @"★★★★★";
    
    rect = self.bounds;
    UIFont *font = [UIFont boldSystemFontOfSize:_starSize];
    CGSize starSize = [stars sizeWithFont:font];
    rect.size=starSize;
    [_emptyColor set];
    [stars drawInRect:rect withFont:font];
    
    CGRect clip = rect;
    clip.size.width = clip.size.width * _showStar / _maxStar;
    CGContextClipToRect(context,clip);
    [_fullColor set];
    [stars drawInRect:rect withFont:font];
}

- (void)dealloc
{
    [_emptyColor release];
    [_fullColor release];
    
    [super dealloc];
}

@end

需要怎么去使用呢？很简单，值需要知道评分是多少就OK啦，比如

//评论是4.2分的
    DisplayStarView *sv = [[DisplayStarView alloc]initWithFrame:CGRectMake(90, 90, 200, 40)];
    [self.view addSubview:sv];
    sv.showStar = 4.2*20;
    [sv release];
    
    //评论是2.5分的
    DisplayStarView *sv1 = [[DisplayStarView alloc]initWithFrame:CGRectMake(90, 90+40, 200, 40)];
    [self.view addSubview:sv1];
    sv1.showStar = 2.5 * 20;
    [sv1 release];
    
    //评论是4.8分的
    DisplayStarView *sv2 = [[DisplayStarView alloc]initWithFrame:CGRectMake(90, 90+40+40, 200, 40)];
    [self.view addSubview:sv2];
    sv2.showStar = 4.8 * 20;
    [sv2 release];

运行结果如图所示：