Swift

Get the Content-ID of a Related Item

Demonstrates the Chilkat Email.GetRelatedContentID method, which returns the Content-ID of a related item (typically an image or style sheet embedded within an HTML email). The index is zero-based. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads that Content-ID back.

Background: The Content-ID is the anchor that ties an inline resource to the HTML that displays it: the body references cid: plus the ID, and the matching related part carries that same Content-ID. Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd. Reading the Content-ID back lets a program verify or rewrite those links — for example when relocating embedded images or converting a message for display outside a mail client.

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func chilkatTest() {
    var success: Bool = false

    //  Demonstrates the GetRelatedContentID method, which returns the Content-ID of a related
    //  item.  Related items are typically images and style sheets embedded within HTML emails.
    //  The index is zero-based.

    let email = CkoEmail()!
    email.subject = "GetRelatedContentID example"

    //  Load the image data from a file into a BinData object.
    let bdImage = CkoBinData()!
    success = bdImage.loadFile(path: "qa_data/images/logo.png")
    if success == false {
        print("\(bdImage.lastErrorText!)")
        return
    }

    //  Add the image as a related item from the BinData; capture its generated Content-ID.
    var cid: String? = email.addRelatedBd(filename: "logo.png", binData: bdImage)
    if email.lastMethodSuccess == false {
        print("\(email.lastErrorText!)")
        return
    }

    //  Reference the related item in the HTML body by its Content-ID.
    let sbHtml = CkoStringBuilder()!
    sbHtml.append(value: "<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>")
    var numReplaced: Int = sbHtml.replace(value: "PLACEHOLDER_CID", replacement: cid).intValue
    email.setHtmlBody(html: sbHtml.getAsString())

    //  Read the Content-ID of the first related item (index 0).
    var cid0: String? = email.getRelatedContentID(index: 0)
    print("Related item 0 Content-ID: \(cid0!)")

    //  Note: The path "qa_data/images/logo.png" is a relative local filesystem path,
    //  relative to the current working directory of the running application.

}