Swift

Receive a 4-byte Length Prefix from a Socket

Demonstrates Socket.ReceiveCount, which reads a four-byte length prefix as a signed 32-bit integer. A return value of -1 indicates failure.

Background. Reading the length prefix first tells the application exactly how many bytes to read for the message body, which is a reliable way to know when a full message has arrived.

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Swift


func chilkatTest() {
    var success: Bool = false

    let socket = CkoSocket()!

    //  Connect to the server using TLS.
    var bTls: Bool = true
    var maxWaitMs: Int = 5000
    success = socket.connect(hostname: "example.com", port: 5000, ssl: bTls, maxWaitMs: maxWaitMs)
    if success == false {
        print("\(socket.lastErrorText!)")
        return
    }

    //  Read a four-byte length prefix as a signed 32-bit integer (network byte order by default).  A
    //  return value of -1 indicates failure.
    var messageLength: Int = socket.receiveCount().intValue
    if messageLength < 0 {
        print("\(socket.lastErrorText!)")
        return
    }

    print("The peer will send \(messageLength) bytes.")

}