Objective-C

Using IMAP IDLE to Wait for Updates

This example demonstrates how to use the IMAP IDLE functionality in Chilkat. Objective-C

#import <CkoImap.h>
#import <NSString.h>

BOOL success = NO;

CkoImap *imap = [[CkoImap alloc] init];

//  ....
//  ....
//  ....

//  Select an IMAP mailbox
success = [imap SelectMailbox: @"INBOX"];
if (success != YES) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  After a mailbox has been selected, IDLE may begin.
//  Idling tells the IMAP server to push unsolicited updates for the selected
//  mailbox to the connected client (which is your application).
success = [imap IdleStart];
if (success != YES) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  Once idling has started, your code still has to periodically check to see
//  if any updates have arrived.  However, this is significantly different
//  then what normally occurs when checking email.  The IdleCheck does NOT
//  send a message to the IMAP server.  It simply checks the connection to see
//  if any data has arrived.  If so, it can be consumed and the client (your app)
//  can react appropriately.  

//  Note: It is recommended that idling only run for a max of 20 minutes before stopping and
//  re-starting the IDLE.  This is to maintain a minimum low level of activity so that 
//  the IMAP server does not disconnect (which it may do if it considers the connection to 
//  be truly inactive, i.e. forgotten).

//  To check the connection for IDLE updates, call IdleCheck.  The 1st argument indicates how
//  long we're willing to wait. We'll wait 1 millisecond:
NSString *idleResultXml = 0;
idleResultXml = [imap IdleCheck: [NSNumber numberWithInt: 1]];
if (imap.LastMethodSuccess != YES) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  See the online reference documentation for details regarding the XML that is returned.
//  Your application code would parse the XML to determine what action to take.
//  If the XML contains "<idle></idle>", then no updates are available and your application
//  would call IdleCheck again at some point in the future.

//  If updates are available, the IDLE must be terminated by calling IdleDone, like this:
success = [imap IdleDone];
if (success != YES) {
    NSLog(@"%@",imap.LastErrorText);
    return;
}

//  Once the IDLE is terminated, your application can make calls to fetch email, etc.
//  Any attempt to communicate with the IMAP server prior to terminating the IDLE will
//  result in failure.

//  IMPORTANT: Please realize that your application code will be structured differently than shown here.
//  The call to IdleCheck will likely be in a function/procedure that is periodically called
//  after the IdleStart has been called from some other location in your app.