Swift

Send and Receive WebSocket Messages

See more WebSocket Examples

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.

Swift

func chilkatTest() {
    var success: Bool = false

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

    let ws = CkoWebSocket()!

    // 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.

    let rest = CkoRest()!
    // 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.
    success = rest.connect(hostname: "websockets.chilkat.io", port: 80, tls: false, autoReconnect: false)
    ws.useConnection(connection: rest)
    ws.addClientHeaders()
    var responseBodyIgnored: String? = rest.fullRequestNoBody(httpVerb: "GET", uriPath: "/wsChilkatEcho.ashx")
    success = ws.validateServerHandshake()
    if success != true {
        print("\(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.
    var finalFrame: Bool = false
    success = ws.sendFrame(stringToSend: "This is the 1st frame\r\n", finalFrame: finalFrame)
    if success != true {
        print("\(ws.lastErrorText!)")
        return
    }

    // Send the 2nd frame in the message.
    success = ws.sendFrame(stringToSend: "This is the 2nd frame\r\n", finalFrame: finalFrame)
    if success != true {
        print("\(ws.lastErrorText!)")
        return
    }

    // Send the 3rd and final frame in the message.
    finalFrame = true
    success = ws.sendFrame(stringToSend: "This is the 3rd frame\r\n", finalFrame: finalFrame)
    if success != true {
        print("\(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.
    var receivedFinalFrame: Bool = false
    while receivedFinalFrame == false {

        success = ws.readFrame()
        if success != true {
            print("Failed to receive a frame")
            print("ReadFrame fail reason = \(ws.readFrameFailReason.intValue)")
            print("\(ws.lastErrorText!)")
            return
        }

        receivedFinalFrame = ws.finalFrame

        // Show the opcode and final frame bit for the frame just received:
        print("Frame opcode: \(ws.frameOpcode!)")
        print("Final frame: \(receivedFinalFrame)")
    }

    // Return the message accumulated in the above calls to ReadFrame.
    var receivedMsg: String? = ws.getFrameData()
    print("Received: \(receivedMsg!)")

    // Close the websocket connection.
    success = ws.sendClose(includeStatus: true, statusCode: 1000, reason: "Closing this websocket.")
    if success != true {
        print("\(ws.lastErrorText!)")
        return
    }

    // Read the Close response.
    success = ws.readFrame()
    if success != true {
        print("ReadFrame fail reason = \(ws.readFrameFailReason.intValue)")
        print("\(ws.lastErrorText!)")
        return
    }

    // Should receive the "Close" opcode.
    print("Received opcode: \(ws.frameOpcode!)")
    // Should be the same status code we sent (1000)
    print("Received close status code: \(ws.closeStatusCode.intValue)")
    // The server may echo the close reason.  If not, this will be empty.
    print("Echoed close reason: \(ws.closeReason!)")

    print("Success.")

}