创建socket stream

转自https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/Streams/Articles/NetworkStreams.html#

//apple_ref/doc/uid/20002277-BCIDFCDI

    The NSStream class does not support connecting to a remote host on iOS. CFStream does support this behavior, however, and once you have created your streams with the CFStream API, you can take advantage of the toll-free bridge between CFStream and NSStream to cast your CFStreams to NSStreams. Just call theCFStreamCreatePairWithSocketToHost function, providing a host name and a port number, to receive both a CFReadStreamRef and a CFWriteStreamRef for the given host. You can then cast these objects to an NSInputStream and an NSOutputStream and proceed.

    Listing 1 illustrates the use of CFStreamCreatePairWithSocketToHost. This example shows the creation of both a CFReadStreamRef object and aCFWriteStreamRef object. If you want to receive only one of these objects, just specify NULL as the parameter value for the unwanted object.

Listing 1  Setting up a network socket stream

- (IBAction)searchForSite:(id)sender

{

    NSString *urlStr = [sender stringValue];

    if (![urlStr isEqualToString:@""]) {

        NSURL *website = [NSURL URLWithString:urlStr];

        if (!website) {

            NSLog(@"%@ is not a valid URL");

            return;

        }

 

        CFReadStreamRef readStream;

        CFWriteStreamRef writeStream;

        CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)[website host], 80, &readStream, &writeStream);

 

        NSInputStream *inputStream = (__bridge_transfer NSInputStream *)readStream;

        NSOutputStream *outputStream = (__bridge_transfer NSOutputStream *)writeStream;

        [inputStream setDelegate:self];

        [outputStream setDelegate:self];

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

        [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

        [inputStream open];

        [outputStream open];

 

        /* Store a reference to the input and output streams so that

           they don't go away.... */

        ...

    }

}

Listing 2  Handling stream event

- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode {

    switch(eventCode)

    {

                    case NSStreamEventOpenCompleted: 
                   {
                             NSLog(@"Opened connection");
                              break;
                    } 
                   case NSStreamEventErrorOccurred: 
                   {
                           NSLog(@"Stream open error");
                           break;
                    } 
        

        case NSStreamEventHasBytesAvailable://Handling a bytes-available event

      {
            if(!_data) {
                _data = [[NSMutableData data] retain];
            }
            uint8_t buf[1024];
            unsigned int len = 0;
            len = [(NSInputStream *)stream read:buf maxLength:1024];
            if(len) {
                [_data appendBytes:(const void *)buf length:len];
                // bytesRead is an instance variable of type NSNumber.
                [bytesRead setIntValue:[bytesRead intValue]+len];
            } else {
                NSLog(@"no buffer!");
            }
            break;
        }
        case NSStreamEventHasBytesAvailable://Handling a space-available event
        {
            if(!_data) {
                _data = [[NSMutableData data] retain];
            }
            uint8_t buf[1024];
            unsigned int len = 0;
            len = [(NSInputStream *)stream read:buf maxLength:1024];
            if(len) {
                [_data appendBytes:(const void *)buf length:len];
                // bytesRead is an instance variable of type NSNumber.
                [bytesRead setIntValue:[bytesRead intValue]+len];
            } else {
                NSLog(@"no buffer!");
            }
            break;
        }
                   case NSStreamEventEndEncountered://Closing and releasing the NSInputStream object
         {
              [stream close];
              [stream removeFromRunLoop:[NSRunLoop currentRunLoop]
                forMode:NSDefaultRunLoopMode];
              [stream release];
              stream = nil; // stream is ivar, so reinit it
              break;
          }

         // continued ...

    }
}