(Objective-C) Send and Receive WebSocket Messages

This example how to send and receive websocket messages.

A WebSocket message can be composed of one or more frames. The simple case is where a single frame is both the first and last frame in a message. This is the case where the 1st frame in the message has the "final frame" bit set.

This example demonstrates sending and receiving multi-frame messages.

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

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#import <CkoWebSocket.h>
#import <CkoRest.h>
#import <NSString.h>

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

CkoWebSocket *ws = [[CkoWebSocket alloc] init];

// For brevity, this example does not check for errors when etablishing the WebSocket connection.
// See Establish WebSocket Connection for more complete sample code for making the connection.

CkoRest *rest = [[CkoRest alloc] init];
// Connect to websockets.chilkat.io
// IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back.
// IMPORTANT: The websockets.chilkat.io server imposes the following limitations: 
// ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.
BOOL success = [rest Connect: @"websockets.chilkat.io" port: [NSNumber numberWithInt: 80] tls: NO autoReconnect: NO];
[ws UseConnection: rest];
[ws AddClientHeaders];
NSString *responseBodyIgnored = [rest FullRequestNoBody: @"GET" uriPath: @"/wsChilkatEcho.ashx"];
success = [ws ValidateServerHandshake];
if (success != YES) {
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// This example demonstrates sending and receiving a multi-frame message.

// The websocket message will be composed of three text lines, each frame will contain a single line.

// Send the 1st frame in the message.
BOOL finalFrame = NO;
success = [ws SendFrame: @"This is the 1st frame\r\n" finalFrame: finalFrame];
if (success != YES) {
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// Send the 2nd frame in the message.
success = [ws SendFrame: @"This is the 2nd frame\r\n" finalFrame: finalFrame];
if (success != YES) {
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// Send the 3rd and final frame in the message.
finalFrame = YES;
success = [ws SendFrame: @"This is the 3rd frame\r\n" finalFrame: finalFrame];
if (success != YES) {
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// Read an incoming frames until we receive the final frame.
// Note: It may be that the echo server (websockets.chilkat.io) responds with 
// the full message in a single final frame.
BOOL receivedFinalFrame = NO;
while (receivedFinalFrame == NO) {

    success = [ws ReadFrame];
    if (success != YES) {
        NSLog(@"%@",@"Failed to receive a frame");
        NSLog(@"%@%d",@"ReadFrame fail reason = ",[ws.ReadFrameFailReason intValue]);
        NSLog(@"%@",ws.LastErrorText);
        return;
    }

    receivedFinalFrame = ws.FinalFrame;

    // Show the opcode and final frame bit for the frame just received:
    NSLog(@"%@%@",@"Frame opcode: ",ws.FrameOpcode);
    NSLog(@"%@%d",@"Final frame: ",receivedFinalFrame);
}

// Return the message accumulated in the above calls to ReadFrame.
NSString *receivedMsg = [ws GetFrameData];
NSLog(@"%@%@",@"Received: ",receivedMsg);

// Close the websocket connection.
success = [ws SendClose: YES statusCode: [NSNumber numberWithInt: 1000] reason: @"Closing this websocket."];
if (success != YES) {
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// Read the Close response.
success = [ws ReadFrame];
if (success != YES) {
    NSLog(@"%@%d",@"ReadFrame fail reason = ",[ws.ReadFrameFailReason intValue]);
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// Should receive the "Close" opcode.
NSLog(@"%@%@",@"Received opcode: ",ws.FrameOpcode);
// Should be the same status code we sent (1000)
NSLog(@"%@%d",@"Received close status code: ",[ws.CloseStatusCode intValue]);
// The server may echo the close reason.  If not, this will be empty.
NSLog(@"%@%@",@"Echoed close reason: ",ws.CloseReason);

NSLog(@"%@",@"Success.");