iOS simple TCP connection example

Question

Does anyone know of a simple TCP example for iOS devices so I can send a string to a server. I've had a look at the following library https://github.com/robbiehanson/CocoaAsyncSocket but it seems very verbose.

All I really want is to have a simple way of connecting to an IP address & port number and sending a string of data to this address. Does anyone know of a simple way to do this?

Answer 1

SocketConnectionVC.h

#import <UIKit/UIKit.h>

@interface SocketConnectionVC : UIViewController<NSStreamDelegate>
{
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;

    NSInputStream   *inputStream;
    NSOutputStream  *outputStream;

    NSMutableArray  *messages;
}

@property (weak, nonatomic) IBOutlet UITextField *ipAddressText;
@property (weak, nonatomic) IBOutlet UITextField *portText;
@property (weak, nonatomic) IBOutlet UITextField *dataToSendText;
@property (weak, nonatomic) IBOutlet UITextView *dataRecievedTextView;
@property (weak, nonatomic) IBOutlet UILabel *connectedLabel;


@end

SocketConnectionVC.m

#import "SocketConnectionVC.h"

@interface SocketConnectionVC ()

@end

@implementation SocketConnectionVC

- (void)viewDidLoad {
    [super viewDidLoad];

    _connectedLabel.text = @"Disconnected";
}

- (IBAction) sendMessage {

    NSString *response  = [NSString stringWithFormat:@"msg:%@", _dataToSendText.text];
    NSData *data = [[NSData alloc] initWithData:[response dataUsingEncoding:NSASCIIStringEncoding]];
    [outputStream write:[data bytes] maxLength:[data length]];

}

- (void) messageReceived:(NSString *)message {

    [messages addObject:message];

    _dataRecievedTextView.text = message;
    NSLog(@"%@", message);
}

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent {

    NSLog(@"stream event %lu", streamEvent);

    switch (streamEvent) {

        case NSStreamEventOpenCompleted:
            NSLog(@"Stream opened");
            _connectedLabel.text = @"Connected";
            break;
        case NSStreamEventHasBytesAvailable:

            if (theStream == inputStream)
            {
                uint8_t buffer[1024];
                NSInteger 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(@"server said: %@", output);
                            [self messageReceived:output];
                        }
                    }
                }
            }
            break;

        case NSStreamEventHasSpaceAvailable:
            NSLog(@"Stream has space available now");
            break;

        case NSStreamEventErrorOccurred:
             NSLog(@"%@",[theStream streamError].localizedDescription);
            break;

        case NSStreamEventEndEncountered:

            [theStream close];
            [theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
            _connectedLabel.text = @"Disconnected";
            NSLog(@"close stream");
            break;
        default:
            NSLog(@"Unknown event");
    }

}

- (IBAction)connectToServer:(id)sender {

    NSLog(@"Setting up connection to %@ : %i", _ipAddressText.text, [_portText.text intValue]);
    CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, (__bridge CFStringRef) _ipAddressText.text, [_portText.text intValue], &readStream, &writeStream);

    messages = [[NSMutableArray alloc] init];

    [self open];
}

- (IBAction)disconnect:(id)sender {

    [self close];
}

- (void)open {

    NSLog(@"Opening streams.");

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

    [outputStream setDelegate:self];
    [inputStream setDelegate:self];

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

    [outputStream open];
    [inputStream open];

    _connectedLabel.text = @"Connected";
}

- (void)close {
    NSLog(@"Closing streams.");
    [inputStream close];
    [outputStream close];
    [inputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [outputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [inputStream setDelegate:nil];
    [outputStream setDelegate:nil];
    inputStream = nil;
    outputStream = nil;

    _connectedLabel.text = @"Disconnected";
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

snapshot for ui of this SocketConnectionVC

and Follow these steps

1- input the ip on ipAdress textfield
2- input the port on port textfield
3- press connect button
4- (make sure the ip address and port is correct and the open of stream is fine. you can show the status of stream on console of Xcode)
5- input data to send to server
6- press send button
7- you can show the received message from server on the text view above connect button