In my project, I always use SLComposeViewController to share contents with third-party apps, but now, when I update my iPhone to iOS 13 GM, this no longer works.
The SLComposeViewControllerCompletionHandler always callback SLComposeViewControllerResultCancelled.
Why is this?
SLComposeViewController has been deprecated since iOS 11. You can either use Social Media's SDK or UIActivityViewController.
Please see this answer