对字符串MD5

/**
 *  数据MD5
 *
 *  @return MD5之后的数据
 */
- (NSString *)stringFromMD5
{
    if(self == nil || [self length] == 0)
        return nil;
    const char *value = [self UTF8String];
    unsigned char outputBuffer[CC_MD5_DIGEST_LENGTH];
    CC_MD5(value, (int)strlen(value), outputBuffer);
    NSMutableString *outputString = [[NSMutableString alloc] initWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
    for(NSInteger count = 0; count < CC_MD5_DIGEST_LENGTH; count++){
        [outputString appendFormat:@"%02X",outputBuffer[count]];
    }
    return outputString;
}

对数字字符格式千位符，如100,000

/**
 *  数字转字符串,带千位符(逗号)
 *
 *  @return 返回带千位符的字符串
 */

- (NSString *)toFormatNumberString
{
    @try
    {
        if (self.length < 3)
        {
            return self;
        }
        NSString *numStr = self;
        NSArray *array = [numStr componentsSeparatedByString:@"."];
        NSString *numInt = [array objectAtIndex:0];
        if (numInt.length <= 3)
        {
            return self;
        }
        NSString *suffixStr = @"";
        if ([array count] > 1)
        {
            suffixStr = [NSString stringWithFormat:@".%@",[array objectAtIndex:1]];
        }

        NSMutableArray *numArr = [[NSMutableArray alloc] init];
        while (numInt.length > 3)
        {
            NSString *temp = [numInt substringFromIndex:numInt.length - 3];
            numInt = [numInt substringToIndex:numInt.length - 3];
            [numArr addObject:[NSString stringWithFormat:@",%@",temp]];//得到的倒序的数据
        }
        int count = (int)[numArr count];
        for (int i = 0; i < count; i++)
        {
            numInt = [numInt stringByAppendingFormat:@"%@",[numArr objectAtIndex:(count -1 -i)]];
        }
        numStr = [NSString stringWithFormat:@"%@%@",numInt,suffixStr];
        return numStr;
    }
    @catch (NSException *exception)
    {
        return self;
    }
    @finally
    {}

}

计算文字据点高度

/**
 *  计算文字的宽高
 *  使用方法 [strText sizeMakeWithFont:[UIFont systemFontOfSize:12] maxW:100];
 *
 *  @param font 字体大小
 *  @param maxW 字体所在的范围的宽度
 *
 *  @return 返回字体所在的范围宽度下的高度。即知道宽，计算高
 */
- (CGSize)sizeMakeWithFont:(UIFont *)font maxW:(CGFloat)maxW
{
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSFontAttributeName] = font;
    CGSize maxSize = CGSizeMake(maxW, MAXFLOAT);

    return [self boundingRectWithSize:maxSize options:NSStringDrawingTruncatesLastVisibleLine|NSStringDrawingUsesLineFragmentOrigin|
            NSStringDrawingUsesFontLeading attributes:attrs context:nil].size;
}

谓词NSPredicate 与正则表达式匹配字符串，参考在线工具

/**
 *  邮箱判定
 *
 *  @return 判定结果
 */
- (BOOL)isValidEmail
{
    NSString *regex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex];
    return [emailTest evaluateWithObject:self];
}