(Swift 2) S3 Upload the Parts for a Multipart Upload

This example uploads a large file in parts. The multipart upload needs to have been first initiated prior to uploading the parts.

See http://docs.aws.amazon.com/AmazonS3/latest/API/mpUploadUploadPart.html for more information about uploading parts.

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func chilkatTest() {
    // In the 1st step for uploading a large file, the multipart upload was initiated
    // as shown here: Initiate Multipart Upload

    // Other S3 Multipart Upload Examples:
    // Complete Multipart Upload
    // Abort Multipart Upload
    // List Parts

    // When we initiated the multipart upload, we saved the XML response to a file.  This
    // XML response contains the UploadId.  We'll begin by loading that XML and getting
    // the Upload ID.

    let xmlInit = CkoXml()
    var success: Bool = xmlInit.LoadXmlFile("s3_multipart_uploads/initiate.xml")
    if success != true {
        print("Did not find the initiate.xml XML file.")
        return
    }

    var uploadId: String? = xmlInit.GetChildContent("UploadId")
    print("UploadId = \(uploadId!)")

    // When uploading parts, we need to keep an XML record of each part number
    // and its corresponding ETag, which is received in the response for each part.
    // There can be up to 10000 parts, numbered 1 to 10000.  
    // After all parts have been uploaded, the final step will be to complete
    // the multipart upload (see Complete Multipart Upload)

    // In this example, the large file we want to upload is somethingBig.zip
    var fileToUploadPath: String? = "s3_multipart_uploads/somethingBig.zip"

    // The minimum allowed part size is 5MB (5242880 bytes).  The last part can be smaller because
    // it will contain the remainder of the file.  (This minimum is enforced by the AWS service.)
    // We'll use the minimum allowed part size for this example.
    var partSize: Int = 5242880

    // Let's use Chilkat's FileAccess API to examine the file to be uploaded.  We'll get the size
    // of the file and find out how many parts will be needed, including the final "partial" part.
    let fac = CkoFileAccess()
    fac.OpenForRead(fileToUploadPath)

    // How many parts will there be if each part is 5242880 bytes?
    var numParts: Int = fac.GetNumBlocks(partSize).intValue
    print("numParts = \(numParts)")
    fac.FileClose()

    // Imagine that we may be running this for the 1st time, or maybe we already
    // attempted to upload parts, and something failed. Maybe there was a network problem
    // the resulted in not all parts getting uploaded.  We'll write this code so that if run again,
    // it will upload whatever parts haven't yet been uploaded.

    // We'll keep a partsList.xml file to record the parts that have already been successfully
    // uploaded.  If this file does not yet exist, we'll create it..
    var partsListFile: String? = "s3_multipart_uploads/partsList.xml"
    let partsListXml = CkoXml()
    if fac.FileExists(partsListFile) == true {
        partsListXml.LoadXmlFile(partsListFile)
    }

    // Make sure the top-level tag is "CompleteMultipartUpload"
    partsListXml.Tag = "CompleteMultipartUpload"

    // --------------------------------------
    // Before entering the loop to upload parts,
    // setup the REST object with AWS authentication,
    // and make the initial connection.
    let rest = CkoRest()

    // Connect to the Amazon AWS REST server.
    var bTls: Bool = true
    var port: Int = 443
    var bAutoReconnect: Bool = true
    success = rest.Connect("s3.amazonaws.com", port: port, tls: bTls, autoReconnect: bAutoReconnect)

    // ----------------------------------------------------------------------------
    // Important: For buckets created in regions outside us-east-1,
    // there are three important changes that need to be made.
    // See Working with S3 Buckets in Non-us-east-1 Regions for the details.
    // ----------------------------------------------------------------------------

    // Provide AWS credentials for the REST call.
    let authAws = CkoAuthAws()
    authAws.AccessKey = "AWS_ACCESS_KEY"
    authAws.SecretKey = "AWS_SECRET_KEY"
    authAws.ServiceName = "s3"
    success = rest.SetAuthAws(authAws)

    // Set the bucket name via the HOST header.
    // In this case, the bucket name is "chilkat100".
    rest.Host = "chilkat100.s3.amazonaws.com"
    // --------------------------------------

    var partNumber: Int = 1
    let sbPartNumber = CkoStringBuilder()

    while (partNumber <= numParts) {
        print("---- \(partNumber) ----")

        // This cumbersome way of converting an integer to a string is because
        // Chilkat examples are written in a script that is converted to many programming languages.
        // At this time, the translator does not have integer-to-string code generation capability..
        sbPartNumber.Clear()
        sbPartNumber.AppendInt(partNumber)

        var bPartAlreadyUploaded: Bool = false

        // If there are no children, then the XML is empty and no parts have yet been uploaded.
        var numUploadedParts: Int = partsListXml.NumChildren.intValue
        if numUploadedParts > 0 {
            // If some parts have been uploaded, check to see if this particular part was already upload.
            // If so, then it can be skipped.

            // Position ourselves at the 1st record.
            var xRec0: CkoXml? = partsListXml.GetChild(0)
            var foundRec: CkoXml? = xRec0!.FindNextRecord("PartNumber", contentPattern: sbPartNumber.GetAsString())
            if xRec0!.LastMethodSuccess == true {
                bPartAlreadyUploaded = true
                print("Part \(partNumber) was previously uploaded.")
                print("\(foundRec!.GetXml())")
                foundRec = nil
            }

            xRec0 = nil
        }

        // If this part was not already uploaded, we need to upload.
        // Also update the partsListXml and save as each part is successfully uploaded.
        if bPartAlreadyUploaded == false {
            print("Uploading part \(partNumber) ...")

            // Setup the stream source for the large file to be uploaded..
            let fileStream = CkoStream()
            fileStream.SourceFile = fileToUploadPath
            // The Chilkat Stream API has features to make uploading a parts
            // of a file easy.  Indicate the part size by setting the SourceFilePartSize
            // property.
            fileStream.SourceFilePartSize = partSize

            // Our HTTP start line to upload a part will look like this:
            // PUT /ObjectName?partNumber=PartNumber&uploadId=UploadId HTTP/1.1

            // Set the query params.  We'll need partNumber and uploadId.
            // Make sure the query params from previous iterations are clear.
            rest.ClearAllQueryParams()
            rest.AddQueryParam("partNumber", value: sbPartNumber.GetAsString())
            rest.AddQueryParam("uploadId", value: uploadId)

            // Upload this particular file part.
            // Tell the fileStream which part is being uploaded.
            // Our partNumber is 1-based (the 1st part is at index 1), but the fileStream's SourceFilePart
            // property is 0-based.  Therefore we use partNumber-1.
            fileStream.SourceFilePart = partNumber - 1

            // Because the SourceFilePart and SourceFilePartSize properties are set, the stream will 
            // will provide just that part of the file.  
            var responseStr: String? = rest.FullRequestStream("PUT", uriPath: "/somethingBig.zip", stream: fileStream)
            if rest.LastMethodSuccess != true {
                print("\(rest.LastErrorText)")
                return
            }

            if rest.ResponseStatusCode.intValue != 200 {
                // Examine the request/response to see what happened.
                print("response status code = \(rest.ResponseStatusCode.intValue)")
                print("response status text = \(rest.ResponseStatusText)")
                print("response header: \(rest.ResponseHeader)")
                print("response body: \(responseStr!)")
                print("---")
                print("LastRequestStartLine: \(rest.LastRequestStartLine)")
                print("LastRequestHeader: \(rest.LastRequestHeader)")
                return
            }

            // OK, this part was uploaded..
            // The response will have a 0-length body.  The only information we need is the 
            // ETag response header field.
            var etag: String? = rest.ResponseHdrByName("ETag")
            // It should be present, but just in case there was no ETag header...
            if rest.LastMethodSuccess != true {
                print("No ETag response header found!")
                print("response header: \(rest.ResponseHeader)")
                return
            }

            // We need to add record to the partsListXml.
            // The record will look like this:
            // &lt;Part>
            //   &lt;PartNumber>PartNumber&lt;/PartNumber>
            //   &lt;ETag>ETag&lt;/ETag>
            // &lt;/Part>
            var xPart: CkoXml? = partsListXml.NewChild("Part", content: "")
            xPart!.NewChildInt2("PartNumber", value: partNumber)
            xPart!.NewChild2("ETag", content: etag)
            xPart = nil

            success = partsListXml.SaveXml(partsListFile)
            if success != true {
                print("\(partsListXml.LastErrorText)")
                return
            }

            print("-- Part \(partNumber) uploaded. ---------------------")
        }

        partNumber = partNumber + 1
    }

    print("Finished.  All parts uploaded.")

}