(Objective-C) Read Bitfinex WebSocket Ticker Channel

Subscribes to the public Bitfinex websocket ticker channel and receives ticker updates.

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#import <CkoWebSocket.h>
#import <CkoRest.h>
#import <NSString.h>
#import <CkoJsonObject.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 api.bitfinex.com
BOOL success = [rest Connect: @"api.bitfinex.com" port: [NSNumber numberWithInt: 443] tls: YES autoReconnect: NO];
[ws UseConnection: rest];
[ws AddClientHeaders];

NSString *responseBody = [rest FullRequestNoBody: @"GET" uriPath: @"/ws"];
success = [ws ValidateServerHandshake];
if (success != YES) {
    NSLog(@"%@",ws.LastErrorText);
    NSLog(@"%@",responseBody);
    NSLog(@"%@",rest.ResponseHeader);
    return;
}

// After connecting, the bitfinex websocket server will send
// an info message that contains the actual version of the websocket stream.
// Receive that message..
success = [ws ReadFrame];
if (success != YES) {
    NSLog(@"%@",@"Failed to receive a frame");
    NSLog(@"%@%d",@"ReadFrame fail reason = ",[ws.ReadFrameFailReason intValue]);
    NSLog(@"%@",ws.LastErrorText);
    return;
}

// We should get this:
// {"event":"info","version":1.1,"platform":{"status":1}}
NSLog(@"%@",[ws GetFrameData]);

// Subscribe to the public ticker feed.
// See https://docs.bitfinex.com/docs for more information.
CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json AppendString: @"event" value: @"subscribe"];
[json AppendString: @"channel" value: @"ticker"];
[json AppendString: @"pair" value: @"BTCUSD"];

BOOL finalFrame = YES;
success = [ws SendFrame: [json Emit] finalFrame: finalFrame];

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

// Examine the response
// We should get this:
// {"event":"subscribed","channel":"ticker","chanId":2751,"pair":"BTCUSD"}
NSLog(@"%@",[ws GetFrameData]);

// Begin reading the ticker feed.
// We'll just read the 1st 5 updates and then exit..
BOOL receivedFinalFrame = NO;
int numUpdatesReceived = 0;
while (numUpdatesReceived < 5) {

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

    // The responses we desire are in Text frames, where the opcode = 1.
    if ([ws.FrameOpcodeInt intValue] == 1) {
        NSString *receivedText = [ws GetFrameData];
        NSLog(@"%@",receivedText);
        // Should receive a line of text such as this:
        // [2751,7349,36.34269559,7349.1,41.01777063,-116.2,-0.0156,7349.1,22188.26055319,7560,7270.5]
        numUpdatesReceived = numUpdatesReceived + 1;
    }

}

// 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;
}

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