Notification Features Improvements

[nesimtunc]

We got 2 new issues @umurgdk

1. When user changes notification permission from iOS Settings, and comes back to CoThings Notification Settings (where left via "Allow Notifications" button), that button will be there because onAppear method doesn't call when the screen re-appear.

2. CoThingsBackend doesn't have the latest list of the rooms when connecting in the background.

Shall we merge this pull request and create these issues as bugs?

Originally posted by @nesimtunc in #36 (comment)

[ishansharma]

Since this is tagged good first issue, I'd be happy to take a look. Do you want to merge it or should I look at PR and get the fix ready and then merge both?

[nesimtunc]

This is not urgent, @umurgdk might be already working on it, but let's consider after you done with #9 issue.

Thank youuuuu @ishansharma

[umurgdk]

@ishansharma @nesimtunc Unfortunately I will not be able to work on the project for a little while. So @ishansharma please welcome to make any improvements.