Objective-C

Add a Custom Header to an Email Attachment

Demonstrates the Chilkat Email.AddAttachmentHeader method, which adds a custom MIME header field to an existing attachment identified by its zero-based index. This example adds an attachment (which becomes index 0), then attaches an extra header field to it and prints the resulting MIME.

Background: In MIME, every attachment is itself a mini-message with its own small block of headers — things like Content-Type, Content-Disposition, and Content-Transfer-Encoding that describe that specific part. AddAttachmentHeader lets you insert additional fields into that per-part header block, which is occasionally needed for interoperability with systems that look for custom X- headers or content identifiers on individual attachments.

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Objective-C

#import <CkoEmail.h>

//  Demonstrates the AddAttachmentHeader method, which adds a custom MIME header field to
//  an existing attachment, identified by its zero-based index.

CkoEmail *email = [[CkoEmail alloc] init];
email.Subject = @"Attachment with a custom header";
email.Body = @"The attachment has an extra MIME header.";

//  Add an attachment; it becomes attachment index 0.
[email AddStringAttachment: @"data.txt" str: @"Attachment body."];

//  Add a custom header field to the first attachment (index 0).
[email AddAttachmentHeader: [NSNumber numberWithInt: 0] fieldName: @"X-Custom-Attachment-Header" fieldValue: @"some value"];

//  The custom header now appears in the attachment's MIME part.
NSLog(@"%@",[email GetMime]);