NSStream TCP Keep-alive iOS

问题描述

我已编写此代码以使用服务器设置流：

I have written this code to setup a stream with a server:

-(void)streamOpenWithIp:(NSString *)ip withPortNumber:(int)portNumber;
{
       CFReadStreamRef readStream;
       CFWriteStreamRef writeStream;
       CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, (__bridge CFStringRef)ip, portNumber, &readStream, &writeStream);

       if(readStream && writeStream)
       {
            CFReadStreamSetProperty(readStream, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
            CFWriteStreamSetProperty(writeStream, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);

            //Setup inpustream
            inputStream = (__bridge NSInputStream *)readStream;
            [inputStream setDelegate:self];
            [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
            [inputStream open];

            //Setup outputstream
            outputStream = (__bridge NSOutputStream *)writeStream;
            [outputStream setDelegate:self];
            [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
            [outputStream open];
       }
}

我能够连接到服务器并发送和放大器;接收数据。但我想检查连接是否仍然存在。如果我从wifi路由器断开电缆，我仍然可以在流中发送数据并且没有发生错误。

I am able to connect to the server and send & receive data. But I want to check if the connection is still there. If I disconnect a cable from the wifi router, I still can send data in the stream and no error occurred.

您可以通过使用计时器在应用程序级别解决此问题。发送一些消息并检查您是否收到回复的信息。但是你也可以用较低级别的TCP Keep-Alive技术解决这个问题。

You can solve this on application level by using a timer to send some message and check if you receive something back. But you can solve this also with TCP Keep-Alive technique on a lower level.

如何用NSStream实现这个？如何设置检查间隔？

How do I implement this with NSStream? How can I set the checking interval?

我假设您通过使用TCP Keep-Alive检查流来关闭流时会得到NSStreamEventErrorOcurred？

I assume that you get a NSStreamEventErrorOcurred when the stream is down by checking it with TCP Keep-Alive?

我已经查过这篇文章，但我无法弄明白：

I have checked this post, but I can't figure it out:Keeping a socket connection alive in iOS

感谢您的帮助！

推荐答案

您可以使用

CFDataRef socketData = CFReadStreamCopyProperty((__bridge CFReadStreamRef)(inputStream), kCFStreamPropertySocketNativeHandle);
CFSocketNativeHandle socket;
CFDataGetBytes(socketData, CFRangeMake(0, sizeof(CFSocketNativeHandle)), (UInt8 *)&socket);
CFRelease(socketData);

然后设置套接字选项（你需要 #include< sys / socket.h> for this）：

and then set socket options (you need to #include <sys/socket.h> for this):

int on = 1;
if (setsockopt(socket, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) {
   NSLog(@"setsockopt failed: %s", strerror(errno));
}

您可以将此代码放在<$ c $的事件处理函数中c> kCFStreamEventOpenCompleted 事件：

You could put this code in the event handler function for the kCFStreamEventOpenCompleted event:

- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)event {
    switch (event) {
        case kCFStreamEventOpenCompleted:
            if (stream == self.inputStream) {
                CFDataRef socketData = CFReadStreamCopyProperty((__bridge CFReadStreamRef)(stream), kCFStreamPropertySocketNativeHandle);
                CFSocketNativeHandle socket;
                CFDataGetBytes(socketData, CFRangeMake(0, sizeof(CFSocketNativeHandle)), (UInt8 *)&socket);
                CFRelease(socketData);

                int on = 1;
                if (setsockopt(socket, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) {
                    NSLog(@"setsockopt failed: %s", strerror(errno));
                }
            }
            break;

        /* ... other cases ... */;
    }
}

这篇关于NSStream TCP Keep-alive iOS的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！