(Swift) Set a Custom Last-Modified Date in a Gzip File

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This example demonstrates how to use the SetDt method to specify a custom last-modified date and time that will be embedded in a Gzip file.

A CkDateTime object is first initialized with a specific date/time using an RFC 822 formatted string. This date/time is then applied to the Gzip object using SetDt.

When a compression method is called (such as CompressStringToFile), the specified date/time is included in the Gzip metadata. This allows the resulting .gz file to carry a meaningful timestamp rather than using the current system time.

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func chilkatTest() {
    var success: Bool = false

    // This example demonstrates how to set a custom last-modified date/time
    // that will be embedded in a Gzip file.

    let gzip = CkoGzip()!
    let dt = CkoDateTime()!

    // Set the date/time using a timestamp format (ISO 8601 style):
    dt.setFromTimestamp("2025-11-15T12:45:26-05:00")

    // Apply the date/time to the Gzip object:
    success = gzip.setDt(dt)
    if success == false {
        print("\(gzip.lastErrorText!)")
        return
    }

    // Compress a string so the custom date/time is embedded in the .gz:
    var inputStr: String? = "Example text for Gzip compression."
    success = gzip.compressString(toFile: inputStr, destCharset: "utf-8", destPath: "output.gz")
    if success == false {
        print("\(gzip.lastErrorText!)")
        return
    }

    print("Gzip file created with custom last-modified date.")

}