将 NSData 复制到 UnsafeMutablePointer<Void>

Question

你好Whosebugers。我正在为安全传输实现一个包装器，但我坚持使用某些 C -> Swift 语法。

func sslReadCallback(connection: SSLConnectionRef,
    data: UnsafeMutablePointer<Void>,
    var dataLength: UnsafeMutablePointer<Int>) -> OSStatus
{
    //let bytesRequested = dataLength.memory
    let transportWrapper:SecureTransportWrapper = UnsafePointer(connection).memory
    let bytesRead:NSData = transportWrapper.readFromConnectionFunc(transportWrapper.connection)
    
    dataLength = UnsafeMutablePointer<Int>.alloc(1)
    dataLength.initialize(bytesRead.length)
    
    if (bytesRead.length == 0)
    {
        return OSStatus(errSSLClosedGraceful)
    }
    else
    {
        data.alloc(sizeof(bytesRead.length)) //<----compile error here
        return noErr
    }
}

编译错误的位置我已经标出来了。我不怪它犯错，我在这里有点猜测：P。我正在尝试将 NSData 复制到 data:UnsafeMutablePointer。我该怎么做？

编译错误：

/Users/*/SecureTransportWrapper.swift:108:9: Static member 'alloc' cannot be used on instance of type 'UnsafeMutablePointer' (aka 'UnsafeMutablePointer<()>')

非常感谢！

================

更新：这是关于 sslReadCallback 应该做什么的 api 文档：

connection: A connection reference.

data: On return, your callback should overwrite the memory at this location with the data read from the connection.

dataLength: On input, a pointer to an integer representing the length of the data in bytes. On return, your callback should overwrite that integer with the number of bytes actually transferred.

摘自here

Answer 1

好的，让我们看一下您的代码：

dataLength = UnsafeMutablePointer<Int>.alloc(1)
dataLength.initialize(bytesRead.length)

dataLength 是你传入的指针，它是函数的调用者给你缓冲区大小的地方和希望你把您读取的字节数。你不需要分配这个，它已经分配了。

（与此示例无关，但：同样在 alloc(N) 和 initialize(N) 中，N 应该相同（它是分配的内存量，然后初始化））

我想你想要的（Swift 3 使用 pointee 而不是 memory）是这样的：

dataLength.memory = bytesRead.length

C API 表示您还可以从该变量中获得 data 缓冲区的大小。 data 将为此大小预先分配。

确保你读取的数据适合(bytesRead.length <= dataLength.memory)，然后做一个

memcpy(data, bytesRead.bytes, bytesRead.length)

就这些了。

将 NSData 复制到 UnsafeMutablePointer<Void>

copy NSData to UnsafeMutablePointer<Void>

c

swift

swift2

unsafe-pointers

secure-transport