(Swift 3,4,5...) FTP Connect, Examine Server Certificate, and then Authenticate

Demonstrates how to connect to an FTP server, examine the server's SSL/TLS certificate, and then, if it meets the application's security requirements, proceed to authenticate.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // This example assumes Chilkat Ftp2 to have been previously unlocked.
    // See Unlock Ftp2 for sample code.

    let ftp = CkoFtp2()!

    ftp.hostname = "www.authtls-ftps-server.com"
    ftp.username = "FTP_LOGIN"
    ftp.password = "FTP_PASSWORD"
    ftp.authTls = true
    ftp.port = 21

    // Connect to the FTP server using explicit TLS (AUTH TLS).
    var success: Bool = ftp.connectOnly()
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    // Get the FTP server's certificate.
    var serverCert: CkoCert? = ftp.getSslServerCert()
    if ftp.lastMethodSuccess != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    // Now that we have the certificate, we can check it in any way we desire.
    // (See the online reference documentation for the certificate object's methods
    // and properties)...

    // Assuming the certificate is OK, proceed to authenticate with the FTP server.
    success = ftp.loginAfterConnectOnly()
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    // 
    // Proceed with uploading/download files, etc...
    // 

    ftp.disconnect()
    print("Success.")

}