A Boolean value that indicates whether the current content and attachments are valid.
- iOS 8.0+
- macOS 10.10+
YES if the current content and attachments are valid for posting, otherwise
NO. The default return value is
This method is automatically called after each change a user makes to the text in the compose view. You can use this method to determine whether the Post button should be enabled and to update
characters, if necessary.
A subclass should implement this method to perform custom validation of the user’s content before initiating a post.