十六进制字符串转数字

+ (NSNumber *) numberHexString:(NSString *)aHexString
{
    // 为空,直接返回.
    if (nil == aHexString)
    {
        return nil;
    }
    
    NSScanner * scanner = [NSScanner scannerWithString:aHexString];
    unsigned long long longlongValue;
    [scanner scanHexLongLong:&longlongValue];
    
    //将整数转换为NSNumber,存储到数组中,并返回.
    NSNumber * hexNumber = [NSNumber numberWithLongLong:longlongValue];
    
    return hexNumber;
}