Fixes header assignment

[drdaz]

It looks like iOS notification headers aren't actually being set. This became most obvious recently with the required headers for iOS 13, as described in parse-community/parse-server#6106

This PR alters header generation so that the supported apns headers are set.

[dplewis]

@drdaz Thanks for the PR. I left a few comments.

[dplewis]

Closing as headers are sent properly and throughly tested.

Please check the push notification guide

[drdaz]

I'm testing them, and they really don't work without these modifications. Have you personally verified this end-to-end?

[drdaz]

@dplewis if you want to see the issue, set priority to anything other than 10 when sending the notification. You'll see in the device console when the notification is received that the priority is always 10. Which breaks silent notifications in iOS 13.

EDIT: Or set any of the other apns header fields actually.

[dplewis]

@drdaz Sorry for jumping to conclusions 😅.

I'm trying to determine if the issue is with this module or the parse-server-push-adapter that uses this module.

I don't think there is an issue with this module, but to be sure I'll open a PR to make testing easier.