Objective c GCDAsyncSocket未接收所有传输的数据，缺少“last”；“块”；

我试图将一些字符串和图像数据从python脚本发送到运行在OSX上的objective C应用程序

我使用GCDAsyncSocket收集传输的数据，并将其附加到NSMutableData，直到服务器断开连接。然后我处理这些数据，并将其拆分为原始部分

传输的数据包括以下内容：

ID字符串，填充为16字节

图像编号字符串，填充为16字节

原始图像数据

终止字符串，填写为16字节

问题是，我没有接收/获取最后一块数据，最终丢失了JPEG图像的结尾，导致图像损坏（尽管大部分显示）和终止字符串丢失

以下是我使用GCDAsyncSocket获取数据并对其进行处理的代码：

插座连接：

- (void)socket:(GCDAsyncSocket *)sock didAcceptNewSocket:(GCDAsyncSocket *)newSocket
{
// This method is executed on the socketQueue (not the main thread)

@synchronized(connectedSockets)
{
    [connectedSockets addObject:newSocket];
}

NSString *host = [newSocket connectedHost];
UInt16 port = [newSocket connectedPort];

dispatch_async(dispatch_get_main_queue(), ^{
    @autoreleasepool {

        [self logInfo:FORMAT(@"Accepted client %@:%hu", host, port)];

    }
});

[newSocket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];

}

接收到套接字数据

- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
// This method is executed on the socketQueue (not the main thread)

dispatch_async(dispatch_get_main_queue(), ^{
    @autoreleasepool {

        NSLog(@"Thread Data Length is %lu", (unsigned long)[data length]);
        if (!imageBuffer){
            imageBuffer = [[NSMutableData alloc]init];
        }

        [imageBuffer appendData:[data subdataWithRange:NSMakeRange(0, [data length])]];
        NSLog(@"Total Data Length is %lu", (unsigned long)[imageBuffer length]);

    }
});

// Echo message back to client
[sock writeData:data withTimeout:-1 tag:ECHO_MSG];
    [sock readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];
}

- (void)socketDidDisconnect:(GCDAsyncSocket *)sock withError:(NSError *)err
{
if (sock != listenSocket)
{
    dispatch_async(dispatch_get_main_queue(), ^{
        @autoreleasepool {

            [self logInfo:FORMAT(@"Client Disconnected")];
            NSData *cameraNumberData;
            NSData *imageNumberData;
            NSData *imageData;
            NSData *endCommandData;
            //if ([data length] > 40){
            cameraNumberData = [imageBuffer subdataWithRange:NSMakeRange(0, 16)];
            imageNumberData = [imageBuffer subdataWithRange:NSMakeRange(16, 16)];
            imageData = [imageBuffer subdataWithRange:NSMakeRange(32, [imageBuffer length]-34)];
            endCommandData = [imageBuffer subdataWithRange:NSMakeRange([imageBuffer length]-16, 16)];
            //}
            NSString *cameraNumberString = [[NSString alloc] initWithData:cameraNumberData encoding:NSUTF8StringEncoding];
            NSString *imageNumberString = [[NSString alloc] initWithData:imageNumberData encoding:NSUTF8StringEncoding];
            NSString *endCommandString = [[NSString alloc] initWithData:endCommandData encoding:NSUTF8StringEncoding];
            NSImage* image = [[NSImage alloc]initWithData:imageData];
            if (cameraNumberString)
            {
                NSLog(@"Image recieved from Camera no %@", cameraNumberString);
                [self logMessage:cameraNumberString];
            }
            else
            {
                [self logError:@"Error converting received data into UTF-8 String"];
            }

            if (imageNumberString)
            {
                NSLog(@"Image is number %@", imageNumberString);
                [self logMessage:imageNumberString];
            }
            else
            {
                [self logError:@"Error converting received data into UTF-8 String"];
            }

            if (image)
            {
                NSLog(@"We have an image");
                [self.imageView setImage:image];
            }
            else
            {
                [self logError:@"Error converting received data into image"];
            }

            if (endCommandString)
            {
                NSLog(@"Command String is %@", endCommandString);
                [self logMessage:endCommandString];
            }
            else
            {
                [self logError:@"No command string"];
            }

            //self.imageBuffer = nil;

        }
    });

        @synchronized(connectedSockets)
    {
        [connectedSockets removeObject:sock];
    }
}
}

插座断开连接

- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
// This method is executed on the socketQueue (not the main thread)

dispatch_async(dispatch_get_main_queue(), ^{
    @autoreleasepool {

        NSLog(@"Thread Data Length is %lu", (unsigned long)[data length]);
        if (!imageBuffer){
            imageBuffer = [[NSMutableData alloc]init];
        }

        [imageBuffer appendData:[data subdataWithRange:NSMakeRange(0, [data length])]];
        NSLog(@"Total Data Length is %lu", (unsigned long)[imageBuffer length]);

    }
});

// Echo message back to client
[sock writeData:data withTimeout:-1 tag:ECHO_MSG];
    [sock readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:0];
}

- (void)socketDidDisconnect:(GCDAsyncSocket *)sock withError:(NSError *)err
{
if (sock != listenSocket)
{
    dispatch_async(dispatch_get_main_queue(), ^{
        @autoreleasepool {

            [self logInfo:FORMAT(@"Client Disconnected")];
            NSData *cameraNumberData;
            NSData *imageNumberData;
            NSData *imageData;
            NSData *endCommandData;
            //if ([data length] > 40){
            cameraNumberData = [imageBuffer subdataWithRange:NSMakeRange(0, 16)];
            imageNumberData = [imageBuffer subdataWithRange:NSMakeRange(16, 16)];
            imageData = [imageBuffer subdataWithRange:NSMakeRange(32, [imageBuffer length]-34)];
            endCommandData = [imageBuffer subdataWithRange:NSMakeRange([imageBuffer length]-16, 16)];
            //}
            NSString *cameraNumberString = [[NSString alloc] initWithData:cameraNumberData encoding:NSUTF8StringEncoding];
            NSString *imageNumberString = [[NSString alloc] initWithData:imageNumberData encoding:NSUTF8StringEncoding];
            NSString *endCommandString = [[NSString alloc] initWithData:endCommandData encoding:NSUTF8StringEncoding];
            NSImage* image = [[NSImage alloc]initWithData:imageData];
            if (cameraNumberString)
            {
                NSLog(@"Image recieved from Camera no %@", cameraNumberString);
                [self logMessage:cameraNumberString];
            }
            else
            {
                [self logError:@"Error converting received data into UTF-8 String"];
            }

            if (imageNumberString)
            {
                NSLog(@"Image is number %@", imageNumberString);
                [self logMessage:imageNumberString];
            }
            else
            {
                [self logError:@"Error converting received data into UTF-8 String"];
            }

            if (image)
            {
                NSLog(@"We have an image");
                [self.imageView setImage:image];
            }
            else
            {
                [self logError:@"Error converting received data into image"];
            }

            if (endCommandString)
            {
                NSLog(@"Command String is %@", endCommandString);
                [self logMessage:endCommandString];
            }
            else
            {
                [self logError:@"No command string"];
            }

            //self.imageBuffer = nil;

        }
    });

        @synchronized(connectedSockets)
    {
        [connectedSockets removeObject:sock];
    }
}
}

我用过wireshark，数据正在传输，只是没有通过GCDAsynSocket

所以，我显然错过了一些东西。像这样的套接字编程和数据编码/解码对我来说是比较新的，所以我可能是个白痴

非常感谢您的帮助

谢谢

---

Gareth

好的，我终于让它工作了。它涉及修改Python中的传输代码，以便在数据的末尾发送一个完成字符串，并对此进行监视。最大的收获是，每次套接字读取一些数据时，我都需要重新调用readDataToData:方法，否则它会坐在那里等待，传输套接字也会坐在那里

我还必须实现使用标记重新调用第二个接收，以便将接收到的数据存储在NSMutableArray中正确的NSMutableData对象中，否则我无法知道第一次接收后数据来自哪个传输套接字，因为ID仅位于第一条消息的开头

以下是didReadData代码：

- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{

dispatch_async(dispatch_get_main_queue(), ^{
    @autoreleasepool {

        NSInteger cameraNumberNumber = 0;
        NSString *cameraNumberString = [[NSString alloc]init];

        if (tag > 10){

            cameraNumberNumber = tag-11;
            DDLogVerbose(@"Second data loop, tag is %ld", tag);
        } else {

        NSData *cameraNumberData;
        //if ([data length] > 40){
        cameraNumberData = [data subdataWithRange:NSMakeRange(0, 16)];
        NSString *cameraNumberString = [[NSString alloc] initWithData:cameraNumberData encoding:NSUTF8StringEncoding];
        cameraNumberString = [cameraNumberString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
        cameraNumberNumber = [cameraNumberString intValue]-1;

        }

        if (cameraNumberNumber+1 <= self.images.count){

                if ([self.images objectAtIndex:cameraNumberNumber] == [NSNull null]){
                        image* cameraImage = [[image alloc]init];
                        [self.images replaceObjectAtIndex: cameraNumberNumber withObject:cameraImage];
                    }

                image* cameraImage = [self.images objectAtIndex:cameraNumberNumber];
                [cameraImage.imageData appendData:[data subdataWithRange:NSMakeRange(0, [data length])]];
                cameraImage.cameraNumber = cameraNumberString;

                if (!imageBuffer){
                        imageBuffer = [[NSMutableData alloc]init];
                    }


                [imageBuffer appendData:[data subdataWithRange:NSMakeRange(0, [data length])]];
                DDLogVerbose(@"Total Data Length is %lu", (unsigned long)[imageBuffer length]);
        } else {

            DDLogInfo(@"Wrong camera quantity!");
            NSAlert *testAlert = [NSAlert alertWithMessageText:@"Wrong camera quantity!"
                                                 defaultButton:@"Ok"
                                               alternateButton:nil
                                                   otherButton:nil
                                     informativeTextWithFormat:@"We have recieved more images than cameras, please set No.Cameras correctly!"];

            [testAlert beginSheetModalForWindow:[self window]
                                  modalDelegate:self
                                 didEndSelector:@selector(stop)
                                    contextInfo:nil];

        }

                [sock readDataToData:[@"end" dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:cameraNumberNumber + 11];

    }

});
}

这里还有我如何修改Python代码以添加额外的“end”标记

---

希望这能帮助其他陷入同样处境的人

也许你不需要发送图像的原始字节，你可以使用一些更粗糙的传输编码，例如base64。Hi Hyperboreus，这是一个很好的观点，可能会提高效率。然而，它不能解释为什么字符串解码失败？是的，它不能回答你的问题（因为我不知道答案），这就是我写评论的原因。事实上，有效点：）嗨，Hyperboreus，我已经用更多信息更新了我上面的问题，任何进一步的输入都将不胜感激！