Objective-C

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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Objective-C

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

//  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.

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

//  Add the text-based related resource first; capture the generated Content-ID.
NSString *cid = [email AddRelatedString: @"styles.css" str: @"body { color: navy; }" charset: @"utf-8"];
if (email.LastMethodSuccess == NO) {
    NSLog(@"%@",email.LastErrorText);
    return true;
}

//  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.
CkoStringBuilder *sbHtml = [[CkoStringBuilder alloc] init];
[sbHtml Append: @"<html><head><link rel=\"stylesheet\" href=\"cid:PLACEHOLDER_CID\"/></head><body>Styled content.</body></html>"];
int numReplaced = [[sbHtml Replace: @"PLACEHOLDER_CID" replacement: cid] intValue];
[email SetHtmlBody: [sbHtml GetAsString]];

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