Objective-C

Enumerate the Header Fields of an Email

Demonstrates the read-only Chilkat Email.NumHeaderFields property together with GetHeaderFieldName and GetHeaderFieldValue to enumerate every header field. Indexing is zero-based, so fields run from 0 to NumHeaderFields - 1. Repeated header fields (a field name that appears more than once) are counted separately. This example builds a small email and prints each header field.

Background: A header field is a single Name: value line at the top of a MIME message. The same field name can legitimately appear multiple times — for example, a message can carry several Received lines, one added by each mail server it passed through. That is why enumerating by index (rather than looking up by name) matters: it lets you see every occurrence in the order it appears.

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Objective-C

#import <CkoEmail.h>

//  Demonstrates the read-only Email.NumHeaderFields property and enumerating each
//  header field by zero-based index using GetHeaderFieldName and GetHeaderFieldValue.

CkoEmail *email = [[CkoEmail alloc] init];
email.Subject = @"Header field enumeration";
email.From = @"mary@example.com";
[email AddTo: @"Joe" emailAddress: @"joe@example.com"];

int n = [email.NumHeaderFields intValue];
NSLog(@"%@%d",@"NumHeaderFields = ",n);

int i;
for (i = 0; i <= n - 1; i++) {
    NSLog(@"%@%@%@",[email GetHeaderFieldName: [NSNumber numberWithInt: i]],@": ",[email GetHeaderFieldValue: [NSNumber numberWithInt: i]]);
}