ios - Swift 中的校验和和 XOR

Question

我在 Objective-C 中编写了这些方法。它们只是校验和和 XOR 一些 NSData

- (void)XOR:(NSMutableData *)inputData withKey:(NSData *)key
{
    unsigned char* inputByteData = (unsigned char*)[inputData mutableBytes];
    unsigned char* keyByteData   = (unsigned char*)[key bytes];
    for (int i = 0; i < [inputData length]; i++)
    {
        inputByteData[i] = inputByteData[i] ^ keyByteData[i % [key length]];
    }
}

- (Byte)checkSum:(NSMutableData *)data withLength:(Byte)dataLength
{
    Byte * dataByte = (Byte *)malloc(dataLength);
    memcpy(dataByte, [data bytes], dataLength);

    Byte result = 0;
    int count = 0;
    while (dataLength>0) {
        result += dataByte[count];
        dataLength--;
        count++;
    };
    result = result&0xff;
    return result&0xff;
}

但是，我不熟悉按位运算符，尤其是在 Swift 中，这些 UnsafeMutablePointer<Void> ... 东西。

谁能帮我转换这个？ (基本上，我需要校验和和 XOR 函数)
还有一件事，他们应该放在 NSData/NSMutableData 中吗？扩展？

谢谢。

Answer 1

UnsafeBufferPointer/UnsafeMutableBufferPointer 可能是您现在需要的。我已经尝试将您的代码翻译成下面的 Swift。 (但是代码没有测试好。)

func XOR(inputData: NSMutableData, withKey key: NSData) {
    let b = UnsafeMutableBufferPointer<UInt8>(start:
        UnsafeMutablePointer(inputData.mutableBytes), count: inputData.length)

    let k = UnsafeBufferPointer<UInt8>(start:
        UnsafePointer(key.bytes), count: key.length)

    for i in 0..<inputData.length {
        b[i] ^= k[i % key.length]
    }
}

func checkSum(data: NSData) -> Int {
    let b = UnsafeBufferPointer<UInt8>(start:
        UnsafePointer(data.bytes), count: data.length)

    var sum = 0
    for i in 0..<data.length {
        sum += Int(b[i])
    }
    return sum & 0xff
}