(Swift 3,4,5...) Download GMail Message Attachment by ID

Demonstrates how to download a GMail email attachment by the attachment ID.

For more information, see https://developers.google.com/gmail/api/v1/reference/users/messages/attachments/get

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 http = CkoHttp()!
    var success: Bool

    http.authToken = "ACCESS_TOKEN"
    http.accept = "application/json"

    // See the following example:  Get GMail Message (format=full)
    // It shows how to download an email by message ID, and it shows how to parse the JSON
    // response which includes attachment names, ids, and other information.

    // This example will assume we already have the attachment id and filename.

    // This is the attachment ID for a file named "helloWorld.pdf".
    var attachmentId: String? = "ANGjdJ-oy3aCuZISJKLAhUdaEksCEklbAPyMaWzFgqOMGbPCRkgwgeu_Kttd99C17OBTHROkDZGekibTKWXGfscB5ww7fw4E65_V1dQ-jHhb2TD1Cdm58-BbNw2iDxzptco8iILPiSnLLfFn5Ps7nsRcxHaGTt3r0yqFKCuIYNnPK1vM04BXI_cfzo-HnI4I3tD6oHNHOGVQrL01MdShFQjPELPUjXM8z1qs7Kom-QyvV1iOldUN-66UuhynsmDX-CMM5TIdB-8KD_lmdhf-0DqG8JnCA20XpXyfqwS8XFkPA-t-QSjb7SdkHQFtQ4lz2PcBREFzZ2eI5j0l0Y_dQHRPYTeMwkVl1yl4MfFT4C4iso3VSF-eqaIjiFCbXKCFNyeEIW5WFsv189dhlSqU"

    var messageId: String? = "1712bc1dc22da2a2"

    http.setUrlVar("messageId", value: messageId)
    http.setUrlVar("attachmentId", value: attachmentId)

    var url: String? = "https://www.googleapis.com/gmail/v1/users/userId/messages/{$messageId}/attachments/{$attachmentId}"

    // When we download, the response is JSON that contains the attachment data base64url encoded, like this:
    // {
    //  "size": 934,
    //  "data": "JVBERi0xLjM ... CiUlRU9GCg=="
    // }

    var outputFilePath: String? = "qa_output/helloWorld.pdf"

    // Download into a StringBuilder.
    let sbJson = CkoStringBuilder()!
    success = http.downloadSb(url, charset: "utf-8", sb: sbJson)
    if success == false {
        print("\(http.lastErrorText!)")
        return
    }

    if http.lastStatus.intValue != 200 {
        // Something failed.
        // the JSON contains an error message.
        print("\(sbJson.getAsString()!)")
        return
    }

    // Load into a Chilkat JSON object.
    let json = CkoJsonObject()!
    success = json.loadSb(sbJson)

    // Extract the base64url data into a BinData.
    let bd = CkoBinData()!
    success = json.bytes(of: "data", encoding: "base64url", bd: bd)

    // Save the data to a file.
    success = bd.writeFile("qa_output/helloWorld.pdf")

    print("Success.")

}