Prevent stops application with NSStream in polling mode

Question

I have implemented a client-server transferring from Windows desktop application to iPhone App. I transfer data using NSStream in polling mode (synchronous).

CFReadStreamRef readStream;
CFWriteStreamRef writeStream;

CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)urlStr, portNo, &readStream, &writeStream);

inputStream = (NSInputStream *)readStream;
outputStream = (NSOutputStream *)writeStream;

[inputStream open];
[outputStream open];

All works fine, but when I attempt to connect an inexistent server or a disconnected server or the port number/ip address is wrong, the WRITE method of NSOutputStream object, stops the application execution.

const uint8_t *str = (uint8_t *) [strRichiesta cStringUsingEncoding:NSASCIIStringEncoding];
[outputStream write:str maxLength:strlen((char*)str)]; 

Is it possible to manage the method by inserting timeout control? If yes, how can I do?

I think that the same problem occurs also with READ method of NSInputStream object.

Could someone help me, please?

Answer 1

Check the NSStreams' streamStatus and streamError functions before trying to use them for reading and writing. See Apple's NSStream Documentation for more info.

This also may help: Setting Up Socket Streams

EDIT: NSStreamStatus values:

typedef enum {
    NSStreamStatusNotOpen = 0,
    NSStreamStatusOpening = 1,
    NSStreamStatusOpen = 2,
    NSStreamStatusReading = 3,
    NSStreamStatusWriting = 4,
    NSStreamStatusAtEnd = 5,
    NSStreamStatusClosed = 6,
    NSStreamStatusError = 7
};

You will have to wait until the status is Open before using it. It may several seconds (maybe even 30 sec) for a bad URL to resolve to status Error.