MFMessageComposeViewControllerTextMessageAvailabilityDidChange
Posted when the current device’s ability to send text messages changes.
Declaration
static let MFMessageComposeViewControllerTextMessageAvailabilityDidChange: NSNotification.NameDiscussion
The system posts this notification when the value canSendText() returns has changed.
Upon receiving this notification, query its userInfo dictionary with the MFMessageComposeViewControllerTextMessageAvailabilityKey key. If the availability of text message sending has changed, your app should invalidate caches and update its user interface as appropriate.