init method
Initiates Firebase Messaging and set the publicVapidKey
.
Implementation
void init(String publicVapidKey) {
if (publicVapidKey.isEmpty) {
throw const FormatException(
'The publicVapidKey can not be null nor can it be an empty string !');
}
_messaging = firebase.messaging();
_messaging.usePublicVapidKey(publicVapidKey);
}