Importance of SLComposeViewControllerCompletionHandler

You need to add the handler(SLComposeViewControllerCompletionHandler) otherwise you may get following error when you try to cancel the Facebook Post or post the Post:

viewServiceDidTerminateWithError:: Error Domain=_UIViewServiceErrorDomain Code =1 "The operation couldn't be completed. (_UIViewServiceErrorDomain error 1.)"


You need to create handler like following

SLComposeViewControllerCompletionHandler __block completionHandler=^(SLComposeViewControllerResult result)

{

            

            [fbController dismissViewControllerAnimated:YES completion:nil];

            

            switch(result){

            case SLComposeViewControllerResultCancelled:

            default:

            {

                NSLog(@"Cancelled.....");

                

            }

                break;

            case SLComposeViewControllerResultDone:

            {

                NSLog(@"Posted....");

            }

                break;

        }};

and add this handler to SLComposeViewController

SLComposeViewController *fbController=[SLComposeViewController composeViewControllerForServiceType:SLServiceTypeFacebook];

[fbController setCompletionHandler:completionHandler];

and you can see the last post to see how to use it completely with the sample code. LINK.