Ios NSOutputStream始终写入零字节

下面就是苹果公司的文档：-我无法让任何网络NSOutputStream写入数据。它总是返回一个苹果的文档似乎说不应该返回的数字（0-苹果声称这是用于固定大小的流，而不是网络流？？）

苹果所有的示例代码都忽略了返回代码（似乎假设它是正数——我在网上发现的很多示例都使用unsigned type！这是非常错误的：（））

我成功地：

CFSocketCreate（），带有kCFSocketAcceptCallBack和指向my handleConnect函数的指针

CFSocketSetAddress（），带有“any”和手动选择的端口

CFRunLoopAddSource（）开始侦听端口

…所有这些都可以工作，通过远程登录到IP地址+端口进行确认

---

…但是，只要遵循苹果的文档，就会出现可怕的错误：

void handleConnect (
                 CFSocketRef s,
                 CFSocketCallBackType callbackType,
                 CFDataRef address,
                 const void *data,
                 void *info
                 )
{
    NSLog(@"handleConnect called with callbackType = %li", callbackType);

    (myclass) server = (myclass*) info;

    BOOL canAccept = callbackType & kCFSocketAcceptCallBack;
    BOOL canWrite = callbackType & kCFSocketWriteCallBack;
    BOOL canRead = callbackType & kCFSocketReadCallBack;
    NSLog(@" ... acceptable? %@  .. readable? %@ .. writeable? %@", canAccept?@"yes":@"no", canRead?@"yes":@"no", canWrite?@"yes":@"no" );

    if( canAccept)
    {
        NSLog(@"[%@] Accepted a socket connection from remote host. Address = %@", [server class], addressString );
        /**
         "which means that a new connection has been accepted. In this case, the data parameter of the callback is a pointer to a CFSocketNativeHandle value (an integer socket number) representing the socket.

         To handle the new incoming connections, you can use the CFStream, NSStream, or CFSocket APIs. The stream-based APIs are strongly recommended."
         */

        // "1. Create read and write streams for the socket with the CFStreamCreatePairWithSocket function."
        CFReadStreamRef clientInput = NULL;
        CFWriteStreamRef clientOutput = NULL;

        // for an AcceptCallBack, the data parameter is a pointer to a CFSocketNativeHandle
        CFSocketNativeHandle nativeSocketHandle = *(CFSocketNativeHandle *)data;

        CFStreamCreatePairWithSocket(kCFAllocatorDefault, nativeSocketHandle, &clientInput, &clientOutput);

        // "2. Cast the streams to an NSInputStream object and an NSOutputStream object if you are working in Cocoa."

        // "3. Use the streams as described in “Writing a TCP-Based Client.”
        self.outputBuffer = [NSMutableData dataWithData:[@"Hello" dataWithEncoding:NSUTF8StringEncoding]];
        self.outputBytesWrittenRecently = 0;
        ((NSOutputStream*)output).delegate = self;

        [((NSOutputStream*)output) scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [((NSOutputStream*)output) open]; // MUST go last, undocumented Apple bug
    }
}

…以及委托方法：

-(void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
{
    BOOL streamOpened = eventCode & NSStreamEventOpenCompleted;
    BOOL streamReadyToWrite = eventCode & NSStreamEventHasSpaceAvailable;
    BOOL streamReadyToRead = eventCode & NSStreamEventHasBytesAvailable;
    BOOL streamEnded = eventCode & NSStreamEventEndEncountered;
    BOOL streamErrored = eventCode & NSStreamEventErrorOccurred;

    if( streamReadyToWrite )
#define C_BUFFER_IN_MEMORY_SIZE_WRITE ( 4096 ) // Apple vaguely recommends 4k, but I tried numbers down to 100 with no effect
    uint8_t extraCBufferNSStreamSucks[ C_BUFFER_IN_MEMORY_SIZE_WRITE ];
    NSRange rangeOfBytesToAttemptToWriteNext = { self.outputBytesWrittenRecently, MIN( C_BUFFER_IN_MEMORY_SIZE_WRITE, self.outputBuffer.length - self.outputBytesWrittenRecently) };
    [self.outputBuffer getBytes:&extraCBufferNSStreamSucks range:rangeOfBytesToAttemptToWriteNext];

    NSLog(@"About to write data to stream, this might block...");
    NSInteger amountWritten = [self.outputS write:extraCBufferNSStreamSucks maxLength:C_BUFFER_IN_MEMORY_SIZE_WRITE];
    NSLog(@"...finished write data to stream, it might have blocked");
    if( amountWritten > 0 )
    {
        self.outputBytesWrittenRecently += amountWritten;

        NSRange totalWrittenRange = { 0, self.outputBytesWrittenRecently };
        NSLog(@"Written %i bytes: %@", amountWritten, [[[NSString alloc] initWithData:[self.outputBuffer subdataWithRange:totalWrittenRange] encoding:NSUTF8StringEncoding] autorelease] );

        if( self.outputBytesWrittenRecently == self.outputBuffer.length )
        {
            NSLog(@"Finished writing data!");

        }
    }
    else
        NSLog(@"ERROR: failed to write bytes to stream (bytes written = %i)", amountWritten);
}

---

啊！未记录，但是…如果您的NSStream实例变为零，而不是返回一个错误，苹果将返回success，但写入的字节数将返回0

在我的例子中，init方法中的一个输入错误意味着我正在用nil覆盖新捕获的NSOutputStream和NSInputStream

---

ARGH.

你的问题是什么？为什么它返回0？有什么问题？缺少什么？为什么API不能像广告中那样工作？我犯了什么错误？我不知道是什么导致了所描述的行为-我只是遵循了苹果的文档-所以我不能更准确地说：（我看到了你的旗帜。我认为这是值得保留的，只是因为没有记录的NSStream问题。同意-我的错误导致了这一点，这是愚蠢的，但根本的问题（苹果糟糕记录的返回代码0）是有效的。而且…由于这个问题，现在谷歌对苹果API的行为进行了攻击/：）。作为记录，在objective-c中，向nil发送消息是完全可以的，它不会起任何作用。因此，如果您的

self.outputS

为nil，则不会返回错误。不会执行任何操作。关于返回0，IMO，这看起来不像是未记录的事情。@nacho4d是的，您关于“发送到nil”的说法是正确的。这是令人困惑的，因为您引用的文档说“如果写入流时出错，返回-1。”-但事实并非如此。这些文档是根据我期望的底层C API编写的，对于Objective-C API来说效果不太好。@nacho4d如果“长度固定且已达到其容量”，则这些文档会说为零。由于网络流根据定义不是固定长度…因此您不希望该方法返回零。