iOS富文本之数字小角标

/// 字符串数字小角标
/// @param text 文本
/// @param size 角标字体
+(NSMutableAttributedString*)getNumberSubscriptString:(NSString*)text size:(CGFloat)size
{
    if (text.length == 0) {return nil;}
    
    NSMutableArray *numStrArr = [NSMutableArray array];
    NSMutableAttributedString *attributedStr = [[NSMutableAttributedString alloc]initWithString:text.uppercaseString];
    
    NSScanner *scanner = [NSScanner scannerWithString:text];
    NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
    
    while (![scanner isAtEnd]) {
        [scanner scanUpToCharactersFromSet:numbers intoString:NULL];
        int number;
        [scanner scanInt:&number];
        
        NSString *num=[NSString stringWithFormat:@"%d",number];
        [numStrArr addObject:num];
    }
    
    if (numStrArr.count) {
        
        NSRange range = NSMakeRange(0, 0);
        for (int i = 0; i < numStrArr.count; i++) {
            range = [text rangeOfString:numStrArr[i]];
            [attributedStr addAttribute:NSFontAttributeName
                                  value:[UIFont systemFontOfSize:size]
                                  range:range];
        }
        
        
    }else{
        [attributedStr addAttribute:NSFontAttributeName
                              value:[UIFont systemFontOfSize:size]
                              range:NSMakeRange(0, text.length)];
    }
    return attributedStr;
}