(Swift 3,4,5...) REST Download Bandwidth Throttle

Demonstrates how to use download bandwidth throttling with the REST API. This example will download a file from Drobox using a file stream, with a limit on the bandwidth that can be used for the transfer.

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.

    // A Dropbox access token should have been previously obtained.
    // Dropbox access tokens do not expire.
    // See Dropbox Access Token.

    // To use bandwidth throttling, the connection should be made using the socket API.
    // This provides numerous properties to customize the connection, such as
    // BandwidthThrottleDown, BandwidthThrottleUp, ClientIpAddress, ClintPort, Http Proxy,
    // KeepAlive, PreferIpv6, RequireSslCertVerify, SoRcvBuf, SoSndBuf, SoReuseAddr,
    // SOCKS proxy, TcpNoSDelay, TlsPinSet, TlsCipherSuite, SslAllowedCiphers, etc.

    let socket = CkoSocket()!
    var maxWaitMs: Int = 5000
    var success: Bool = socket.connect("content.dropboxapi.com", port: 443, ssl: true, maxWaitMs: maxWaitMs)
    if success != true {
        print("\(socket.lastErrorText!)")
        print("Connect Fail Reason: \(socket.connectFailReason.intValue)")
        return
    }

    // Set the download bandwidth throttle rate to 50000 bytes per second.
    socket.bandwidthThrottleDown = 50000

    let rest = CkoRest()!

    // Tell the REST object to use the connected socket.
    rest.useConnection(socket, autoReconnect: true)

    // The remainder of this example is identical to the example at:
    // Dropbox Download File.

    // Add request headers.
    rest.addHeader("Authorization", value: "Bearer DROPBOX_ACCESS_TOKEN")

    // The download "parameters" are contained in JSON passed in an HTTP request header.
    // This is the JSON indicating the file to be downloaded:
    // { 
    //    "path": "/Homework/lit/hamlet.xml",
    // }

    let json = CkoJsonObject()!
    json.append("path", value: "/Homework/lit/hamlet.xml")
    rest.addHeader("Dropbox-API-Arg", value: json.emit())

    // Setup a file stream for the download
    let fileStream = CkoStream()!
    fileStream.sinkFile = "qa_output/hamletFromDropbox.xml"

    // Indicate that the call to FullRequestNoBody should send the response body
    // to fileStream if the response status code is 200.
    // If a non-success response status code is received, then nothing
    // is streamed to the output file and the error response is returned by FullRequestNoBody.
    var expectedStatus: Int = 200
    rest.setResponseBodyStream(expectedStatus, autoSetStreamCharset: true, responseStream: fileStream)

    var responseStr: String? = rest.fullRequestNoBody("POST", uriPath: "/2/files/download")
    if rest.lastMethodSuccess != true {
        print("\(rest.lastErrorText!)")
        return
    }

    // When successful, Dropbox responds with a 200 response code.
    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 (if any): \(responseStr!)")
        print("---")
        print("LastRequestStartLine: \(rest.lastRequestStartLine!)")
        print("LastRequestHeader: \(rest.lastRequestHeader!)")
        return
    }

    // Information about the downloaded file is also available as JSON in a response header.
    // The "dropbox-api-result" response header contains the information.  For example:
    var apiResult: String? = rest.responseHdr(byName: "dropbox-api-result")
    print("\(apiResult!)")

    // In this case, the pretty-formatted dropbox-api-result JSON looks like this:
    // { 
    //   "name": "hamlet.xml",
    //   "path_lower": "/homework/lit/hamlet.xml",
    //   "path_display": "/Homework/lit/hamlet.xml",
    //   "id": "id:74FkdeNuyKAAAAAAAAAAAQ",
    //   "client_modified": "2016-06-02T23:19:00Z",
    //   "server_modified": "2016-06-02T23:19:00Z",
    //   "rev": "9482db15f",
    //   "size": 279658
    // }

    // Load the JSON, pretty-print it, and demonstrate how to get some values...
    let jsonResult = CkoJsonObject()!
    jsonResult.emitCompact = false
    jsonResult.load(apiResult)
    // Show the JSON pretty-printed...
    print("\(jsonResult.emit()!)")

    // Sample code to get data from the JSON response:
    var size: Int = jsonResult.int(of: "size").intValue
    print("size = \(size)")

    var rev: String? = jsonResult.string(of: "rev")
    print("rev = \(rev!)")

    var clientModified: String? = jsonResult.string(of: "client_modified")
    let ckdt = CkoDateTime()!
    ckdt.setFromTimestamp(clientModified)
    var bLocalTime: Bool = true
    var dt: CkoDtObj? = ckdt.getDtObj(bLocalTime)
    print("\(dt!.day.intValue)/\(dt!.month.intValue)/\(dt!.year.intValue) \(dt!.hour.intValue):\(dt!.minute.intValue)")
    dt = nil

}