iOS Push Notification Custom fields not showing

Greetings,

I'm working on an app capable of receiving Push Notifications through the APNS. So far it's been a successful process, but whenever I attempt to send any custom fields along with the notification, they never seem to show up (as in, I get the notification, but without the custom fields).

I'm using a REST client to send the notifications to a device, and this is the payload that I'm currently testing with:

{
    "alert":"whatevs", 
    "m":"message"
}

I've also tried putting the custom field as top-level keys of the payload, as instructed on the official documentation:

{"aps":
    {
        "alert":"whatevs", 
    },
    "m":"message"
}

Using any of these, I only get the alert message. I wonder if I'm missing anything, and I'd appreciate if someone has experience with iOS Push notifications and has managed to tackle this issue.

Thanks.