(Swift 3,4,5...) Xero Download Attachment for an Item (such as an Invoice)

Demonstrates how to download a particular attachment for a particular Xero item.

For more information, see https://developer.xero.com/documentation/api/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()!

    let jsonToken = CkoJsonObject()!
    var success: Bool = jsonToken.loadFile("qa_data/tokens/xero-access-token.json")
    if success == false {
        print("\(jsonToken.lastErrorText!)")
        return
    }

    http.authToken = jsonToken.string(of: "access_token")

    // Replace the value here with an actual tenant ID obtained from this example:
    // Get Xero Tenant IDs
    http.setRequestHeader("Xero-tenant-id", value: "83299b9e-5747-4a14-a18a-a6c94f824eb7")

    http.accept = "application/json"

    // The example to list Xero attachments shows how to get attachment information.
    // Here's a sample JSON response obtained form listing attachments:
    // Your application can get the AttachmentID's and filenames from it.

    // {
    //   "Id": "24bfbcb9-dec9-4d33-835c-8f165d776766",
    //   "Status": "OK",
    //   "ProviderName": "Chilkat2222",
    //   "DateTimeUTC": "\/Date(1587213296972)\/",
    //   "Attachments": [
    //     {
    //       "AttachmentID": "daf106e2-8634-4349-bfcc-86c1df0793b2",
    //       "FileName": "penguins.jpg",
    //       "Url": "https://api.xero.com/api.xro/2.0/Invoices/0032f627-3156-4d30-9b1c-4d3b994dc921/Attachments/penguins.jpg",
    //       "MimeType": "image/jpg",
    //       "ContentLength": 777835
    //     }
    //   ]
    // }

    var url: String? = "https://api.xero.com/api.xro/2.0/{$Endpoint}/{$Guid}/Attachments/{$AttachmentId}"

    // Endpoint can be Invoices, Receipts, CreditNotes, PurchaseOrders, etc.
    http.setUrlVar("Endpoint", value: "Invoices")

    // Guid is the ID of the item, such as the InvoiceID.
    http.setUrlVar("Guid", value: "0032f627-3156-4d30-9b1c-4d3b994dc921")

    // AttachmentId is the ID of the particular attachment to be downloaded
    http.setUrlVar("AttachmentId", value: "daf106e2-8634-4349-bfcc-86c1df0793b2")

    // Download the attachment data into bd.
    let bd = CkoBinData()!
    success = http.quickGetBd(url, binData: bd)
    if success == false {
        print("\(http.lastErrorText!)")
        return
    }

    print("Response Status Code: \(http.lastStatus.intValue)")

    if http.lastStatus.intValue == 200 {
        // Success
        // Save to a file..
        success = bd.writeFile("qa_output/penguines.jpg")
    }
    else {
        // Failed.  bd contains error information..
        print("\(bd.getString("utf-8")!)")
    }


}