Question

我在应用商店中有一个iOS应用。我正在为此开发一些新功能。我正在研究称重机和使用telnet连接在系统中注册重量的要求。使用以下代码，我与称重机建立telnet连接

- (void)initNetworkCommunication {

uint portNo = 23;
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)@"227.3.4.56", portNo, &readStream, &writeStream);
inputStream = (__bridge NSInputStream *)readStream;

[inputStream setDelegate:self];

[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[inputStream open];}

委托方法中接收到的数据

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent {
uint8_t buffer[1024];
int len;

switch (streamEvent) {

    case NSStreamEventOpenCompleted:
        NSLog(@"Stream opened now");
        break;
    case NSStreamEventHasBytesAvailable:
        NSLog(@"has bytes");
        if (theStream == inputStream) {
            while ([inputStream hasBytesAvailable]) {
                len = [inputStream read:buffer maxLength:sizeof(buffer)];
                if (len > 0) {

                    NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];

                    if (nil != output) {
                        NSLog(@"server said: %@", output);
                    }
                }
            }
        } else {
            NSLog(@"it is NOT theStream == inputStream");
        }
        break;
    case NSStreamEventHasSpaceAvailable:
        NSLog(@"Stream has space available now");
        break;


    case NSStreamEventErrorOccurred:
        NSLog(@"Can not connect to the host!");
        break;


    case NSStreamEventEndEncountered:

        [theStream close];
        [theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

        break;

    default:
        NSLog(@"Unknown event %i", streamEvent);
}}

由于该线程被阻塞并且无法执行进一步的代码，因此称重机会在几秒钟内连续发布相同的数据。为了避免这种情况，我要做的是一旦我第一次在NSStreamEventHasBytesAvailable中获取数据，就关闭输入流。

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent {
uint8_t buffer[1024];
int len;

switch (streamEvent) {

    case NSStreamEventOpenCompleted:
        NSLog(@"Stream opened now");
        break;
    case NSStreamEventHasBytesAvailable:
        NSLog(@"has bytes");
        if (theStream == inputStream) {
            while ([inputStream hasBytesAvailable]) {
                len = [inputStream read:buffer maxLength:sizeof(buffer)];
                if (len > 0) {

                    NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];

                    if (nil != output) {
                        NSLog(@"server said: %@", output);

                        [theStream close];
                        [theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
                   }
                }
            }
        } else {
            NSLog(@"it is NOT theStream == inputStream");
        }
        break;
    case NSStreamEventHasSpaceAvailable:
        NSLog(@"Stream has space available now");
        break;


    case NSStreamEventErrorOccurred:
        NSLog(@"Can not connect to the host!");
        break;


    case NSStreamEventEndEncountered:

        [theStream close];
        [theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

        break;

    default:
        NSLog(@"Unknown event %i", streamEvent);
}}

问题说明

关闭连接后，当我尝试在重新连接后下次尝试获取数据时，它总是给出空白响应，并且连接关闭。始终进行重新连接时，我需要数据。请指导

在iOS目标C中从称重机读取重量

0 个答案: