Swift

Compress and Decompress Hex String

See more Compression Examples

Imagine we have data represented as a hex string. This example demonstrates how to decode, compress, and re-encode to a smaller hex string representing the compressed data. An even better choice is to re-encode to a more compact encoding such as base64.

Note: This example requires Chilkat v9.5.0.66 or greater.

Swift

func chilkatTest() {
    var success: Bool = false

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var strHex: String? = "54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A"

    let compress = CkoCompression()!
    compress.algorithm = "deflate"

    let binDat = CkoBinData()!
    // Load the hex string into a BinData object.
    // This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
    binDat.appendEncoded(encData: strHex, encoding: "hex")

    // Compress the BinData.
    compress.compressBd(bd: binDat)

    // Get the compressed data in hex format:
    var compressedHex: String? = binDat.getEncoded(encoding: "hex")
    print("compressed hex:")
    print("\(compressedHex!)")

    // The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

    // Even better, get the compressed data in base64 format:
    // (base64url and modbase64 are other valid choices...)
    var compressedBase64: String? = binDat.getEncoded(encoding: "base64")
    print("compressed base64:")
    print("\(compressedBase64!)")

    // The compressed base64 is: C8lIVSgszUzOVkgqyi/PU0jLr1DIKs0tSE1RyC9LLVIoAcrnJFZVKqTkp+vxcoUMYeW8XAA=

    // Now decompress:
    binDat.clear()
    binDat.appendEncoded(encData: compressedHex, encoding: "hex")
    compress.decompressBd(bd: binDat)

    var decompressedHex: String? = binDat.getEncoded(encoding: "hex")
    print("decompressed hex:")
    print("\(decompressedHex!)")

    // The output is the original hex string:
    // 54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A

}