Objective-C

Control Overwriting When Saving Attachments

Demonstrates the Chilkat Email.OverwriteExisting property. When true (the default), the methods that save attachments and related items overwrite files that already exist. When false, those methods instead append a short 4-character string to create a unique filename, and the filename stored in the email object is updated so your program can discover the actual file(s) created. This setting applies only when writing to the filesystem. This example disables overwriting and saves all attachments.

Background: Attachment filenames come from the sender and are not guaranteed to be unique — two different emails (or even two parts of one email) can both be named invoice.pdf. When saving many attachments into one folder, that collision would silently destroy data if each save overwrote the last. Setting OverwriteExisting to false makes Chilkat generate a distinct name instead, and reading the updated filename back from the object tells you where the file actually landed.

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Objective-C

#import <CkoEmail.h>

BOOL success = NO;

//  Demonstrates the Email.OverwriteExisting property.  When true (the default), the
//  methods that save attachments and related items overwrite existing files.  When
//  false, Chilkat instead creates a unique filename (appending 4 characters) so an
//  existing file is not overwritten.

CkoEmail *email = [[CkoEmail alloc] init];
email.Subject = @"Attachment save demo";
[email AddStringAttachment: @"report.txt" str: @"Attachment contents."];

//  Do not overwrite an existing file; create a unique filename instead.
email.OverwriteExisting = NO;

success = [email SaveAllAttachments: @"qa_output/attachments"];
if (success == NO) {
    NSLog(@"%@",email.LastErrorText);
    return true;
}

NSLog(@"%@%d",@"Saved.  OverwriteExisting = ",email.OverwriteExisting);