利用NSMutableAttributedString属性进行简单的富文本，修改字体大小、字体颜色、文字开头添加图片、价格的中划线

自己创建一个NSString的类别：
创建一个回调block：typedef void(^AttributedBlock)(id data);
1.根据需求页面需要修改一个label里面的文字颜色及大小：

/**
 currentString   当前不需要改变的文字
 chageString     当前需要改变的文字
 endString       结尾字符串
 fontSize        改变的字体大小
 stringColor     改变的颜色
 tag 1:改变颜色。2：改变大小 3.改变颜色和字体
 */

/**改变字体颜色大小*/
+(void)stringWithCurrentString:(NSString *)currentString
              withChangeString:(NSString *)chageString
                     withColor:(UIColor *)stringColor
                       withTag:(NSInteger)tag
                      withFont:(NSInteger)fontSize
                 withEndString:(NSString *)endString
                     withBlock:(AttributedBlock)block;

+(void)stringWithCurrentString:(NSString *)currentString
              withChangeString:(NSString *)chageString
                     withColor:(UIColor *)stringColor
                       withTag:(NSInteger)tag
                      withFont:(NSInteger)fontSize
                 withEndString:(NSString *)endString
                     withBlock:(AttributedBlock)block
{
    NSString * textString = [NSString stringWithFormat:@"%@%@%@",currentString,chageString,endString];
    NSInteger currentStringLength = currentString.length;
    NSInteger chageStringLength = chageString.length;
    NSMutableAttributedString * attributeString = [[NSMutableAttributedString alloc]initWithString:textString];
    if (tag == 1)//改变颜色
    {
        [attributeString addAttribute:NSForegroundColorAttributeName value:stringColor range:NSMakeRange(currentStringLength, chageStringLength)];
    }
    else if (tag == 2)
    {
        [attributeString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:fontSize]    range:NSMakeRange(currentStringLength, chageStringLength)];
    }
    else if (tag == 3)
    {
        [attributeString addAttribute:NSForegroundColorAttributeName value:stringColor range:NSMakeRange(currentStringLength, chageStringLength)];
        [attributeString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:fontSize]    range:NSMakeRange(currentStringLength, chageStringLength)];
    }
    block(attributeString);
}

2.文字前面加图片：

+(void)stringWithImage:(NSString *)currentString
             withBlock:(AttributedBlock)block;

+(void)stringWithImage:(NSString *)currentString
             withBlock:(AttributedBlock)block
{
    NSMutableAttributedString * attributeString = [[NSMutableAttributedString alloc]initWithString:currentString];
    NSTextAttachment *attach = [[NSTextAttachment alloc] init];
    attach.image = [UIImage imageNamed:@"需要添加的图片"];
    attach.bounds = CGRectMake(0, -3, 15, 15);
    NSAttributedString *attachString = [NSAttributedString attributedStringWithAttachment:attach];
    [attributeString insertAttributedString:attachString atIndex:0];
    block(attributeString);
}

3.显示价格的时候需要显示中划线：

/**中划线。价格*/
+(void)stringWithLine:(NSString *)currentString
            withBlock:(AttributedBlock)block;

+(void)stringWithLine:(NSString *)currentString
            withBlock:(AttributedBlock)block
{
    NSMutableAttributedString * attributeString = [[NSMutableAttributedString alloc]initWithString:currentString];
    NSInteger currentStringLength = currentString.length;
    [attributeString addAttribute:NSStrikethroughStyleAttributeName value:@(NSUnderlineStyleSingle) range:NSMakeRange(0, currentStringLength)];
    [attributeString addAttribute:NSStrikethroughColorAttributeName value:[UIColor lightGrayColor] range:NSMakeRange(0, currentStringLength)];
    block(attributeString);
}