Setting up a server for VoIP notifications

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/sideshow/apns2"
	"github.com/sideshow/apns2/certificate"
)

type MessageFrom struct {
	From string `json:"from"`
}
type Message struct {
	APS MessageFrom `json:"aps"`
	//from  string
	//callType string `json:"type"`
}

func sendPush(deviceToken string, from string) {
	//"aps":{"from":"Mehmet"}
	//request := fmt.Sprintf("Hi, %s! Welcome.", name)

	f := MessageFrom{From: from}
	m := Message{f}
	b, err := json.Marshal(m)
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Println(string(b))

	cert, err := certificate.FromP12File("static/Certificates.p12", "D=GYbuK?1d25")
	if err != nil {
		log.Fatal("Cert Error:", err)
	}

	//notificationPayload := payload.NewPayload().Alert("hello").Badge(1).Custom("from", from).Custom("type", "emailAddress")
	//notification.Payload = notificationPayload

	notification := &apns2.Notification{}
	notification.DeviceToken = deviceToken
	notification.Topic = "com.memtarhan.callme.voip"
	notification.Payload = b //[]byte(`{"aps":{"from":"Mehmet"}}`) // See Payload section below
	notification.PushType = "voip"

	// If you want to test push notifications for builds running directly from XCode (Development), use
	// client := apns2.NewClient(cert).Development()
	// For apps published to the app store or installed as an ad-hoc distribution use Production()

	client := apns2.NewClient(cert).Production()
	//client := apns2.NewClient(cert).Development()
	res, err := client.Push(notification)

	if err != nil {
		log.Fatal("Error:", err)
	}

	fmt.Printf("%v\n%v\n%v\n", res.StatusCode, res.ApnsID, res.Reason)
}