TCP Client

This guide is based on the excellent Ray Wenderlick guide

Adding A TCP Client To A ViewController Class

In your #ViewController.h

#import 

@interface MyViewController : UIViewController
				<NSStreamDelegate>		//-ADD THIS
{
	NSInputStream *InputStream;
	NSOutputStream *OutputStream;
	NSMutableData *OutputData;
}

- (void)TcpClientInitialise;
@end

In your #ViewController.m

//**************************************
//**************************************
//********** VIEW WILL APPEAR **********
//**************************************
//**************************************
//View about to be added to the window (called each time it appears)
//Occurs after other view's viewWillDisappear
- (void)viewWillAppear:(BOOL)animated
{
	[super viewWillAppear:animated];

	[self TcpClientInitialise];
}



//*******************************************
//*******************************************
//********** TCP CLIENT INITIALISE **********
//*******************************************
//*******************************************
- (void)TcpClientInitialise
{
	NSLog(@"Tcp Client Initialise");
	
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;
	
	
    CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)@"1.2.3.4", 80, &readStream, &writeStream);

    InputStream = (NSInputStream *)readStream;
    OutputStream = (NSOutputStream *)writeStream;
	
	[InputStream setDelegate:self];
	[OutputStream setDelegate:self];
	
	[InputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
	[OutputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
	
	[InputStream open];
	[OutputStream open];
}

//**********************************
//**********************************
//********** SENDING DATA **********
//**********************************
//**********************************
	NSString *response  = @"HELLO1234";
	NSData *data = [[NSData alloc] initWithData:[response dataUsingEncoding:NSASCIIStringEncoding]];
	[OutputStream write:[data bytes] maxLength:[data length]];	//<<Returns actual number of bytes sent - check if trying to send a large number of bytes as they may well not have all gone in this write and will need sending once there is a hasspaceavailable event


//****************************************
//****************************************
//********** TCP CLIENT RECEIVE **********
//****************************************
//****************************************
- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)StreamEvent
{
	
	switch (StreamEvent)
	{
		case NSStreamEventOpenCompleted:
			NSLog(@"TCP Client - Stream opened");
			break;
			
		case NSStreamEventHasBytesAvailable:
			if (theStream == InputStream)
			{
				uint8_t buffer[1024];
				int len;
				
				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(@"TCP Client - Server sent: %@", output);
						}



						//Send some data (large block where the write may not actually send all we request it to send)
						int ActualOutputBytes = [OutputStream write:[OutputData bytes] maxLength:[OutputData length]];
							
						if (ActualOutputBytes >= ChunkToSendLength)
						{
							//It was all sent
							[OutputData release];
							OutputData = nil;
						}
						else
						{
							//Only partially sent
							[OutputData replaceBytesInRange:NSMakeRange(0, ActualOutputBytes) withBytes:NULL length:0];		//Remove sent bytes from the start
						}
					}
				}
			}
			break;			
			
		case NSStreamEventErrorOccurred:
			NSLog(@"TCP Client - Can't connect to the host");
			break;
			
		case NSStreamEventEndEncountered:
			NSLog(@"TCP Client - End encountered");
			[theStream close];
			[theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
			break;

		case NSStreamEventNone:
			NSLog(@"TCP Client - None event");
			break;
			
		case NSStreamEventHasSpaceAvailable:
			NSLog(@"TCP Client - Has space available event");
			if (OutputData != nil)
			{
				//Send rest of the packet
				int ActualOutputBytes = [OutputStream write:[OutputData bytes] maxLength:[OutputData length]];
			
				if (ActualOutputBytes >= [OutputData length])
				{
					//It was all sent
					[OutputData release];
					OutputData = nil;
				}
				else
				{
					//Only partially sent
					[OutputData replaceBytesInRange:NSMakeRange(0, ActualOutputBytes) withBytes:NULL length:0];		//Remove sent bytes from the start
				}
			}
			break;

		default:
			NSLog(@"TCP Client - Unknown event");
	}
	
}

//*****************************************
//*****************************************
//********** VIEW WILL DISAPPEAR **********
//*****************************************
//*****************************************
//View is about to be dismissed, covered or otherwise hidden from view (called each time it disappers)
//Occurs before other view's viewWillAppear
- (void)viewWillDisappear:(BOOL)animated
{
	[super viewWillDisappear:animated];

	[InputStream close];
	[OutputStream close];
	[InputStream release];
	InputStream = nil;
	[OutputStream release];
	OutputStream = nil;
	if (OutputData != nil)
	{
		[OutputData release];
		OutputData = nil;
	}
}