获取一行文本中 一个连续数字的起始位置和长度

应用场景：一般应用于连续签到的提示，部分文本中需要特殊显示的数字样式

- (NSRange)rangeOfFirstMatchString:(NSString *)str{
    NSError *error = NULL;
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"[0-9]" options:NSRegularExpressionCaseInsensitive | NSRegularExpressionDotMatchesLineSeparators | NSRegularExpressionAnchorsMatchLines | NSRegularExpressionAllowCommentsAndWhitespace error:&error];
    NSRange firstMatchRange = [regex rangeOfFirstMatchInString:str options:0 range:NSMakeRange(0, [str length])];
    NSInteger matches = [regex numberOfMatchesInString:str options:0 range:NSMakeRange(0, [str length])];
    if (matches>1) {
        firstMatchRange.length = firstMatchRange.length + matches - 1;
    }
    return firstMatchRange;
}

接下来就可以利用返回的range值设置attributeString的富文本的属性，例如：

- (void)setAttributeStringForBlackLbl:(NSString *)str{
    if ([NSString contentIsNullORNil:str] ==  NO) {
        NSMutableAttributedString * attributeString = [[NSMutableAttributedString alloc] initWithString:str];
        [attributeString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:16] range:NSMakeRange(0, str.length)];
        [attributeString addAttribute:NSForegroundColorAttributeName value:[UIColor colorFromHexRGB:@"FF533D"] range:NSMakeRange(0, str.length)];
        //设置强调文字
        NSRange specialRange = [self rangeOfFirstMatchString:str];
        [attributeString addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:18.0] range:specialRange];
        [attributeString addAttribute:NSForegroundColorAttributeName value:[UIColor colorFromHexRGB:@"E24C39"] range:specialRange];
        self.blackLbl.attributedText = attributeString;
    }
}