字符串转换为NSdata数据/十进制转换为十六进制

本文链接：https://blog.youkuaiyun.com/buildSetting/article/details/53170027

该博客介绍了如何将字符串转换成NSData数据流，以及如何将十进制数值转换为十六进制字符串。提供了两个方法，一个是将十六进制字符串转换为NSData对象，另一个是将十进制整数转换为对应的十六进制字符串。

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#pragma mark -- 十六进制转换为NSData数据流
+ (NSData *)convertHexStrToData:(NSString *)str {
    if (!str || [str length] == 0) {
        return nil;
    }
    
    NSMutableData *hexData = [[NSMutableData alloc] initWithCapacity:8];
    NSRange range;
    if ([str length] % 2 == 0) {
        range = NSMakeRange(0, 2);
    } else {
        range = NSMakeRange(0, 1);
    }
    for (NSInteger i = range.location; i < [str length]; i += 2) {
        unsigned int anInt;
        NSString *hexCharStr = [str substringWithRange:range];
        NSScanner *scanner = [[NSScanner alloc] initWithString:hexCharStr];
        
        [scanner scanHexInt:&anInt];
        NSData *entity = [[NSData alloc] initWithBytes:&anInt length:1];
        [hexData appendData:entity];
        
        range.location += range.length;
        range.length = 2;
    }
    return hexData;
}
//转换为十六进制
+(NSString *)ToHex:(long long int)tmpid
{
    
    long long int data = tmpid;//大于255的数字转化为4位十六进制
    NSString *nLetterValue;
    NSString *str =@"";
    long long int ttmpig;
    for (int i = 0; i<9; i++) {
        ttmpig=tmpid%16;
        tmpid=tmpid/16;
        switch (ttmpig)
        {
            case 10:
                nLetterValue =@"A";break;
            case 11:
                nLetterValue =@"B";break;
            case 12:
                nLetterValue =@"C";break;
            case 13:
                nLetterValue =@"D";break;
            case 14:
                nLetterValue =@"E";break;
            case 15:
                nLetterValue =@"F";break;
            default:nLetterValue=[[NSString alloc]initWithFormat:@"%lli",ttmpig];
                
        }
        str = [nLetterValue stringByAppendingString:str];
        if (tmpid == 0) {
            break;
        }
        
    }
    if (data > 255) {
        str = [NSString stringWithFormat:@"0%@",str];
    }
    if (data < 16) {
        str = [NSString stringWithFormat:@"0%@",str];
    }
    return str;
}