(Swift 3,4,5...) Synchronize Local Directory Tree

Downloads files from the FTP server to a local directory tree. Synchronization modes include:

mode=0: Download all files
mode=1: Download all files that do not exist on the local filesystem.
mode=2: Download newer or non-existant files.
mode=3: Download only newer files. If a file does not already exist on the local filesystem, it is not downloaded from the server..
mode=5: Download only missing files or files with size differences.
mode=6: Same as mode 5, but also download newer files.
mode=99: Do not download files, but instead delete remote files that do not exist locally.

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

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

    let ftp = CkoFtp2()!

    ftp.hostname = "ftp.example.com"
    ftp.username = "login"
    ftp.password = "password"

    ftp.keepSessionLog = true

    // Connect and login to the FTP server.
    var success: Bool = ftp.connect()
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    // Set the current remote directory to the root of
    // the tree to be downloaded.
    success = ftp.changeRemoteDir("/subDir1")
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    // Recursively download all non-existant and newer files.
    var mode: Int = 2
    success = ftp.syncLocalTree("c:/temp/subDir1", mode: mode)
    if success != true {
        print("\(ftp.lastErrorText!)")
        return
    }

    success = ftp.disconnect()

    // Display the session log.  
    print("\(ftp.sessionLog!)")

}