Method onMessage

packages/firebase-messaging/index.ios.ts:77–85

(listener: (message: RemoteMessage) => any)

	}

	onMessage(listener: (message: RemoteMessage) => any) {
		if (!listener && this._onMessage) {
			this._instance.removeOnMessage(this._onMessage);
		} else {
			this._instance.addOnMessage(listener);
		}

		this._onMessage = listener;
	}

	onToken(listener: (token: string) => any) {
		if (!listener && this._onToken) {