- (void)close { // Empty queues. [self emptyQueues]; [partialReadBuffer release]; partialReadBuffer = nil; [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(disconnect) object:nil]; // Close streams. if (theReadStream != NULL) { CFReadStreamSetClient(theReadStream, kCFStreamEventNone, NULL, NULL); CFReadStreamUnscheduleFromRunLoop (theReadStream, theRunLoop, kCFRunLoopDefaultMode); CFReadStreamClose (theReadStream); CFRelease (theReadStream); theReadStream = NULL; } if (theWriteStream != NULL) { CFWriteStreamSetClient(theWriteStream, kCFStreamEventNone, NULL, NULL); CFWriteStreamUnscheduleFromRunLoop (theWriteStream, theRunLoop, kCFRunLoopDefaultMode); CFWriteStreamClose (theWriteStream); CFRelease (theWriteStream); theWriteStream = NULL; } // Close sockets. if (theSocket != NULL) { CFSocketInvalidate (theSocket); CFRelease (theSocket); theSocket = NULL; } if (theSocket6 != NULL) { CFSocketInvalidate (theSocket6); CFRelease (theSocket6); theSocket6 = NULL; } if (theSource != NULL) { CFRunLoopRemoveSource (theRunLoop, theSource, kCFRunLoopDefaultMode); CFRelease (theSource); theSource = NULL; } if (theSource6 != NULL) { CFRunLoopRemoveSource (theRunLoop, theSource6, kCFRunLoopDefaultMode); CFRelease (theSource6); theSource6 = NULL; } theRunLoop = NULL; // If the client has passed the connect/accept method, then the connection has at least begun. // Notify delegate that it is now ending. if (theFlags & kDidPassConnectMethod) { // Delay notification to give him freedom to release without returning here and core-dumping. if ([theDelegate respondsToSelector: @selector(onSocketDidDisconnect:)]) { //[theDelegate performSelector:@selector(onSocketDidDisconnect:) withObject:self afterDelay:0]; [theDelegate onSocketDidDisconnect:self]; } } // Clear flags. theFlags = 0x00; }

这段代码是 CocoaAsyncSocket 库中的 Socket 类的 close 方法。该方法关闭了当前连接并释放了相关资源，如果连接已经开始，则通知代理连接已经结束。其中 `[theDelegate onSocketDidDisconnect:self]` 代码行是通知代理连接已经断开的代码行，如果代理实现了 `onSocketDidDisconnect:` 方法，则该方法将被调用并传递当前的 Socket 实例作为参数。这个方法通常用于通知应用程序当前连接已经断开，以便应用程序可以再次尝试连接或者进行其他处理。