(Swift 2) Streaming Compression

Compress and decompress using a stream.

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

    let fac = CkoFileAccess()
    let compress = CkoCompression()
    compress.Algorithm = "deflate"

    let streamC = CkoStream()

    // This example sets the source and sink of the stream to files.
    // A stream can have use other streams as a source or sink,
    // or the application can itself be the source/sink by directly
    // reading or writing a stream.  (See below for an example of this..)
    streamC.SourceFile = "qa_data/hamlet.xml"
    streamC.SinkFile = "qa_output/hamlet_compressed.dat"

    // Compress from source to sink.
    var success: Bool = compress.CompressStream(streamC)
    if success != true {
        print("\(compress.LastErrorText)")
        return
    }

    print("File-to-file deflate compression successful.")
    // Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
    // the size of the file as a string, then convert to an integer value.
    print("Original size = \(fac.FileSize(streamC.SourceFile).intValue)")
    print("Compressed size = \(fac.FileSize(streamC.SinkFile).intValue)")

    // Now do file-to-file decompression
    let streamD = CkoStream()
    streamD.SourceFile = "qa_output/hamlet_compressed.dat"
    streamD.SinkFile = "qa_output/hamlet_restored.xml"

    // Decompress from source to sink.
    success = compress.DecompressStream(streamD)
    if success != true {
        print("\(compress.LastErrorText)")
        return
    }

    print("File-to-file deflate decompression successful.")

    // Let's double-check to see that the files are equal in size and content:

    var bFilesEqual: Bool = fac.FileContentsEqual(streamC.SourceFile, path2: streamD.SinkFile)
    if bFilesEqual != true {
        print("The output file is not equal to the input file!")
    }
    else {
        print("The file was successfully compressed and decompressed.")
    }

    // ---------------------------------------------------------------------
    // Now let's decompress again, but this time w/ the application reading
    // the decompressed data directly from a stream.
    let streamA = CkoStream()

    streamA.SourceFile = "qa_output/hamlet_compressed.dat"

    // Start decompressing in a background thread.
    var task: CkoTask? = compress.DecompressStreamAsync(streamA)
    success = task!.Run()

    // Read decompressed data from streamA:
    var decompressedText: String?
    while (streamA.EndOfStream != true) {
        if streamA.DataAvailable == true {
            decompressedText = streamA.ReadString()
            print("\(decompressedText!)")
        }

    }

    // Let's make sure the background task finished and that the decompress was successful.
    // It should already be the case that the task is finished.
    while (task!.Finished != true) {
        task!.SleepMs(20)
    }

    // The decompressor may have finished, but it is possible that data
    // remains to be flushed.  
    if streamA.DataAvailable == true {
        decompressedText = streamA.ReadString()
        print("\(decompressedText!)")
    }

    // Did streamA succeed in reading the entire file?
    if task!.TaskSuccess != true {
        print("async decompress failed:")
        print("\(task!.ResultErrorText)")
        success = false
    }

    print("The async decompress was successful.")

}