ios - NSInputStream 缓冲区的大小
<p><p>我正在尝试使用 NSInputStream 通过 TCP 套接字连接接收数据。在服务器端，我在发送<strong>数据本身</strong>之前发送<strong>数据大小</strong>。在 iOS 客户端，我需要从 NSInputStream 中提取前 4 个字节，因为我需要检查数据大小是否已完全接收，但我遇到了问题:</p>
<pre><code>...
case NSStreamEvent.HasBytesAvailable:
if ( aStream == inputstream){
while (inputstream.hasBytesAvailable){
var readBufferRef = UnsafeMutablePointer<UnsafeMutablePointer<UInt8>>()
var readBufferLengthRef = 0
let readBufferIsAvailable = inputstream.getBuffer(readBufferRef, length: &readBufferLengthRef)
...
}
}
break
</code></pre>
<p>接收到数据后readBufferLengthRef总是等于0。</p>
<p>怎么可能？ </p>
<p>我如何获得 NSInputStream 缓冲区的大小？</p>
<p><strong>UPD:</strong></p>
<p>代码:</p>
<pre><code>case NSStreamEvent.HasBytesAvailable:
NSLog("HasBytesAvaible")
var buffer = (count: 1024, repeatedValue: 0)
if ( aStream == inputstream){
while (inputstream.hasBytesAvailable){
var readBufferRef: UnsafeMutablePointer<UInt8> = nil
var readBufferLengthRef = 0
let readBufferIsAvailable = inputstream.getBuffer(&readBufferRef, length: &readBufferLengthRef)
//debugger: readBufferLengthRef = (int)0
}
}
break
</code></pre></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>在您的代码中，<code>readBufferRef</code> 被定义为“指向指针的指针”
但从未分配，因此它是 NULL 指针。</p>
<p>你应该做的是传递一个<em>地址</em>
<code>UnsafeMutablePointer<UInt8></code> 作为函数的 inout 参数
(假设 Swift 2):</p>
<pre><code>var readBufferRef: UnsafeMutablePointer<UInt8> = nil
var readBufferLengthRef = 0
let readBufferIsAvailable = inputStream.getBuffer(&readBufferRef, length: &readBufferLengthRef)
</code></pre>
<p>返回时，<code>readBufferRef</code> 设置为流的读取缓冲区(直到下一次读取操作有效)，<code>readBufferLengthRef</code> 包含
可用字节数。</p></p>
<p style="font-size: 20px;">关于ios - NSInputStream 缓冲区的大小，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/40045665/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/40045665/
</a>
</p>
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