How to create APNS payload for Firebase?

Question

I have connected my IONIC 4 app to Firebase and then to AWS SNS. Everything works perfectly for Android, the push notifications are delivered. But iOS devices never receives them. I have made all the necessary configs, certificates and keys. When I publish a test message via Firebase Console, the iOS devices receive the notifications.

I get a little confuse about this payload object and I guess it might be causing this issue.

The payload object (ignore the values):

var payload = {
  default: "Trokaí",
  GCM: {
    data: { message: "A", payload: "", title: "C" },
    notification: {
      message: "E",
      payload: "F",
      title: "Trokaí",
      body: msgPush
    }
  },
  APNS: {
    aps: {
      alert: {
        title: "Game Request",
        body: "Bob wants to play poker",
        "action-loc-key": "PLAY"
      },
      badge: 5
    },
    acme1: "bar",
    acme2: ["bang", "whiz"]
  }
};

payload.GCM = JSON.stringify(payload.GCM);
payload.APNS = JSON.stringify(payload.APNS);

payload = JSON.stringify(payload);

The publishing method:

 sns.publish(
    {
      Message: payload,
      MessageStructure: "json",
      TargetArn: device.endpoint
    },
    function(err, data) {
      if (err) {
        return;
      }
    }