Objective-C

Get a Header Attribute of a Related Item

Demonstrates the Chilkat Email.GetRelatedAttr method, which returns a header-field attribute value from a header field of the Nth related item. The first argument is the zero-based related-item index, the second names a header field, and the third names an attribute within it. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads the name attribute of the related item's Content-Type header.

Background: Related items (inline images, style sheets) are MIME parts whose headers may carry named parameters — for instance Content-Type: image/png; name="logo.png". Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd, rather than being treated as text. GetRelatedAttr then extracts one named attribute from a chosen header of a specific related part, the related-item analogue of GetAttachmentAttr, so you don't have to parse the raw header yourself.

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Objective-C

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

BOOL success = NO;

//  Demonstrates the GetRelatedAttr method, which returns a header-field attribute value
//  from a header field of the Nth related item.  The first argument is the zero-based related-item
//  index, the second is the header field name, and the third is the attribute name.

CkoEmail *email = [[CkoEmail alloc] init];
email.Subject = @"GetRelatedAttr example";

//  Load the image data from a file into a BinData object.
CkoBinData *bdImage = [[CkoBinData alloc] init];
success = [bdImage LoadFile: @"qa_data/images/logo.png"];
if (success == NO) {
    NSLog(@"%@",bdImage.LastErrorText);
    return true;
}

//  Add the image as a related item from the BinData; capture its generated Content-ID.
NSString *cid = [email AddRelatedBd: @"logo.png" binData: bdImage];
if (email.LastMethodSuccess == NO) {
    NSLog(@"%@",email.LastErrorText);
    return true;
}

//  Reference the related item in the HTML body by its Content-ID.
CkoStringBuilder *sbHtml = [[CkoStringBuilder alloc] init];
[sbHtml Append: @"<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>"];
int numReplaced = [[sbHtml Replace: @"PLACEHOLDER_CID" replacement: cid] intValue];
[email SetHtmlBody: [sbHtml GetAsString]];

//  Get the "name" attribute of the related item's Content-Type header (index 0).
NSString *val = [email GetRelatedAttr: [NSNumber numberWithInt: 0] fieldName: @"Content-Type" attrName: @"name"];
NSLog(@"%@%@",@"Related item Content-Type name attribute: ",val);

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