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Swift

Send a 4-byte Length Prefix over a Socket

See more Socket/SSL/TLS Examples

Demonstrates Socket.SendCount, which sends a four-byte length prefix in network byte order. This is typically used to tell the peer how many bytes follow.

Background. A length-prefixed framing scheme sends the byte count of a message before the message body, so the receiver knows exactly how many bytes to read with a counted receive.

Chilkat Swift Downloads

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
    }

    //  Send a four-byte length prefix in network byte order.  A common framing pattern is to send the
    //  number of bytes in a message before the message itself, so the peer knows exactly how many bytes
    //  to read.
    var messageLength: Int = 512
    success = socket.sendCount(byteCount: messageLength)
    if success == false {
        print("\(socket.lastErrorText!)")
        return
    }

    print("Length prefix sent.")

}