IOS低水平系列化

问题描述：

下面是一个Java / Android的功能：

Here is a Java / Android function:

public static byte[] serialize(MyClass myObject) {

    int byteArraySizeNeeded = getByteArraySizeNeededForSerialize(myObject);

    byte[] result = new byte[byteArraySizeNeeded];
    ByteBuffer bb = ByteBuffer.wrap(result);
    bb.putShort((short) (byteArraySizeNeeded-2));// 2 - not need to read at deserialisation!

    bb.putLong(myObject.getProperty1ValueWhichIsALong());// 8
    bb.putDouble(myObject.getProperty2ValueWhichIsADouble());// 8
    bb.putFloat(myObject.getProperty3ValueWhichIsAFloat);//4
    bb.put(CODE_MYCODE1); // code
    bb.putFloat(myObject.getProperty4ValueWhichIsAFloat);

// there are a lot of properties and the list is dynamic: some need to be saved some not: eg if property 10 exists than not needed to save property 11 and property 25 is saved only if not null and so on.

    int curPosition = bb.position();
    int offset = 2; // skip the first 2 bytes representing the size of byte buffer needed to allocate.
    int byteCount = curPosition - offset;

    myObject.crc.update(result, offset, byteCount);
    long crcValue = myObject.crc.getValue();

    bb.put(CODE_CRC); // code
    bb.putLong(crcValue);// only distinct data values

    return result;
}

我想在iOS的做太多。或者，我想还是找不到一个低级的数据结构/类中使用的。

I would like to do at iOS too. Or I miss or can't find a low level data structure / class what to use.

NSData的和 NSMutableData A>算得上是一个对象，它封装了一个字节数组，但他们有效功能只在 dataContentsOfFile 和将writeToFile 。

NSData and NSMutableData claim to be an object which wraps a byte array, but they usefully function is only the dataContentsOfFile and writeToFile.

NSArchiver 是像一个ObjectOutputStream。

NSArchiver is like an ObjectOutputStream.

档案和序列化编程指南
无法找到这把关键例如en codeBytes不需要任何方法：长：forKey：

Archives and Serializations Programming Guide Can't find any method which not required to put a key like encodeBytes:length:forKey:

我不希望推倒重来，也不能挽救使用了很多不必要的数据。

I don't want to reinvent the wheel, nor use a lot of unnecessary data at saving.

是具有putLong（）putFloat（）putInt（任何工具类），并char或字节数组正确？

Is any utility class which has a putLong() putFloat() putInt() and make a char or byte array properly?

答

我发现the同样的问题以及这个答案是基于它。您可以轻松地创建一个实现使用相同的接口的ByteBuffer NSOutputStream 。事情是这样的：结果

I've found the same question and this answer is based on it. You can easily create a class that implements the same interface as ByteBuffer using NSOutputStream. Something like this:

- (NSOutputStream*)outputStream {
    if (_outputStream == nil) {
        _outputStream = [[NSOutputStream alloc] initToMemory];
        [_outputStream open];
    }
    return _outputStream;
}

- (void)putInt:(NSInteger)value {
    [self.outputStream write:(uint8_t*)&value maxLength:sizeof(NSInteger)];
}

- (NSData*)data {
    return [self.outputStream propertyForKey:NSStreamDataWrittenToMemoryStreamKey];
}

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