Objective-C

Add a Related File to an HTML Email

Demonstrates the Chilkat Email.AddRelatedFile method, which adds the contents of a local file as a related MIME resource and returns the generated Content-ID. The returned value is the bare Content-ID — no angle brackets and no cid: prefix — so if it returns CID-123@example, the HTML reference is cid:CID-123@example. Because the Content-ID is generated by the call, this example adds the image first, then builds the HTML body in a StringBuilder — using a placeholder in the <img> tag that is replaced with the returned Content-ID — and passes the result to SetHtmlBody.

Background: To embed an image so it displays inside an HTML email (rather than being downloaded from a web server), you add it as a "related" part and reference it from the HTML with a cid: URL that matches the part's Content-ID. Since Chilkat assigns that ID when you add the file, the natural order is: add the related file, capture the returned ID, then build the <img src="cid:..."> reference from it. A StringBuilder makes assembling and updating the HTML convenient.

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Objective-C

#import <CkoEmail.h>
#import <NSString.h>
#import <CkoStringBuilder.h>

//  Demonstrates the AddRelatedFile method, which adds a local file as a related MIME
//  resource (such as an image displayed by an HTML body) and returns the generated
//  Content-ID.  The HTML references the item using cid:<Content-ID>.

CkoEmail *email = [[CkoEmail alloc] init];
email.Subject = @"Email with a related image";

//  Add the image file as a related item first.  The return value is the bare Content-ID
//  (no angle brackets and no "cid:" prefix).
NSString *cid = [email AddRelatedFile: @"qa_data/images/logo.png"];
if (email.LastMethodSuccess == NO) {
    NSLog(@"%@",email.LastErrorText);
    return true;
}

//  Build the HTML body in a StringBuilder, using a placeholder where the image's
//  Content-ID will go.
CkoStringBuilder *sbHtml = [[CkoStringBuilder alloc] init];
[sbHtml Append: @"<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>"];

//  Replace the placeholder with the actual Content-ID returned by AddRelatedFile.
int numReplaced = [[sbHtml Replace: @"PLACEHOLDER_CID" replacement: cid] intValue];

//  Set the HTML body from the StringBuilder result.
[email SetHtmlBody: [sbHtml GetAsString]];

NSLog(@"%@%@",@"Related Content-ID = ",cid);
NSLog(@"%@%d",@"NumRelatedItems = ",[email.NumRelatedItems intValue]);

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