Objective-C

Get the Content-ID of an Attachment

Demonstrates the Chilkat Email.GetAttachmentContentID method, which returns the Content-ID header field for the Nth attachment. The index is zero-based, so the first attachment is 0. This example adds an attachment and reads its Content-ID (which may be empty when none was assigned).

Background: A Content-ID is a unique identifier for a MIME part. It is essential for inline "related" resources, where HTML references an image by cid:, but ordinary file attachments usually have none. Reading it is useful when inspecting how a message is assembled, or when distinguishing parts that are referenced from the body versus those meant purely as downloadable attachments.

Chilkat Objective-C Downloads

Download Chilkat for Objective-C

Objective-C

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

//  Demonstrates the GetAttachmentContentID method, which returns the Content-ID header
//  field for the Nth attachment.  The index is zero-based (the first attachment is 0).

CkoEmail *email = [[CkoEmail alloc] init];
email.Subject = @"Attachment Content-ID";

[email AddStringAttachment: @"notes.txt" str: @"Some notes."];

//  Get the Content-ID of the first attachment (may be empty if none was assigned).
NSString *cid = [email GetAttachmentContentID: [NSNumber numberWithInt: 0]];
NSLog(@"%@%@",@"Attachment 0 Content-ID: ",cid);