Swift

Add a Related String Resource to an Email

Demonstrates the Chilkat Email.AddRelatedString method, which adds a text-based related MIME resource, such as a style sheet, from an in-memory string and returns the generated Content-ID. The first argument is the MIME resource name, the second is the text content, and the third is the charset used to encode it. Because the Content-ID is generated by the call, this example adds the style sheet first, then builds an HTML body in a StringBuilder that references the style sheet by that cid:, and passes the result to SetHtmlBody.

Background: Related items are not always images loaded from disk — sometimes the resource is text you already have in memory, like a generated CSS style sheet or an SVG. AddRelatedString lets you embed such content directly without writing a temporary file first. As with other related items, it lives in the multipart/related enclosure and is referenced from the HTML by the Content-ID the method returns.

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Swift


func chilkatTest() {
    //  Demonstrates the AddRelatedString method, which adds a text-based related MIME resource
    //  (such as a style sheet) from an in-memory string and returns the generated Content-ID.
    //  The first argument is the resource name, the second is the text content, the third is the charset.

    let email = CkoEmail()!
    email.subject = "Email with a related style sheet"

    //  Add the text-based related resource first; capture the generated Content-ID.
    var cid: String? = email.addRelatedString(nameInHtml: "styles.css", str: "body { color: navy; }", charset: "utf-8")
    if email.lastMethodSuccess == false {
        print("\(email.lastErrorText!)")
        return
    }

    //  Build the HTML body, referencing the related style sheet by its Content-ID.  A
    //  placeholder is used and then replaced with the actual Content-ID.
    let sbHtml = CkoStringBuilder()!
    sbHtml.append(value: "<html><head><link rel=\"stylesheet\" href=\"cid:PLACEHOLDER_CID\"/></head><body>Styled content.</body></html>")
    var numReplaced: Int = sbHtml.replace(value: "PLACEHOLDER_CID", replacement: cid).intValue
    email.setHtmlBody(html: sbHtml.getAsString())

    print("Related Content-ID = \(cid!)")
    print("NumRelatedItems = \(email.numRelatedItems.intValue)")

}