(Swift) Compress a File to Gzip with Custom Metadata

See more Gzip Examples

This example demonstrates how to use the CompressFile method to create a Gzip (.gz) file while customizing the metadata embedded in the Gzip header.

Before compression, several properties are set:

• Comment: Adds a descriptive comment to the Gzip file.
• Filename: Specifies the filename to embed in the Gzip data, which may be used by extraction tools as the default output name.
• CompressionLevel: Controls the tradeoff between compression ratio and speed (set to maximum in this example).
• LastModStr: Sets the last-modified timestamp using an RFC 822 formatted date string.

After setting these properties, the input file is compressed and written to a .gz file. This approach allows you to embed meaningful metadata along with the compressed data.

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func chilkatTest() {
    var success: Bool = false

    // This example demonstrates how to compress a file to Gzip format
    // while setting custom metadata such as comment, filename,
    // compression level, and last-modified date.

    let gzip = CkoGzip()!

    // Set custom Gzip properties:
    gzip.comment = "Example Gzip file created with Chilkat"
    gzip.filename = "custom_name.txt"
    gzip.compressionLevel = 9
    gzip.lastModStr = "Wed, 1 Apr 2025 12:45:26 -0500"

    // The file to be compressed:
    var inputFile: String? = "example.txt"
    var outputFile: String? = "example.txt.gz"

    // Compress the file:
    success = gzip.compressFile(inputFile, destPath: outputFile)
    if success == false {
        print("\(gzip.lastErrorText!)")
        return
    }

    print("Compression successful.")
    print("Gzip file created: \(outputFile!)")

}