Provisional notifications in iOS

ProvisionalNotifications.swift

	/// Sets up provisional authorization (as in, "trial notifications")
	// see: https://asciiwwdc.com/2018/sessions/710
	fileprivate func requestProvisionalAuthorization() {
		if #available(iOS 12.0, *) {
			let options: UNAuthorizationOptions = [.provisional]
			UNUserNotificationCenter.current().requestAuthorization(options: options) { (authorized, error) in
				if let error = error {
					logger.error(String(describing: error))
				}
			}
		} else {
			logger.info("Not on iOS 12; can't schedule provisional notifications.")
		}
	}