(Swift 3,4,5...) Decompress Large Binary File in Blocks

Decompresses a large binary file in blocks. This example uses BeginDecompressBytes, MoreDecompressBytes, and EndDecompressBytes.

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 facSrc = CkoFileAccess()!
    let facDest = CkoFileAccess()!

    // Open a previously compressed file for decompressing.
    // See Compress Large File in Blocks

    var success: Bool = facSrc.open(forRead: "qa_data/bmp/compressedBmp.dat")
    if success != true {
        print("\(facSrc.lastErrorText!)")
        return
    }

    // If we compress in 32K chunks, find out how many blocks there will be.
    var blockSize: Int = 32768
    var numBlocks: Int = facSrc.getNumBlocks(blockSize).intValue

    // Open an output file for the decompressed data.
    success = facDest.open(forWrite: "qa_output/decompressed.bmp")
    if success != true {
        print("\(facDest.lastErrorText!)")
        return
    }

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

    var decompressedBytes: NSData
    var compressedBytes: NSData

    var i: Int = 0
    while i < numBlocks {
        compressedBytes = facSrc.readBlock(i, blockSize: blockSize)
        if i == 0 {
            decompressedBytes = compress.beginDecompressBytes(compressedBytes)
        }
        else {
            decompressedBytes = compress.moreDecompressBytes(compressedBytes)
        }

        facDest.fileWrite(decompressedBytes)

        i = i + 1
    }

    // At the very end, flush any remaining decompressed bytes, if any.
    decompressedBytes = compress.endDecompressBytes()
    facDest.fileWrite(decompressedBytes)

    facSrc.fileClose()
    facDest.fileClose()

    print("Finished decompressing file.")

}