Rate that app!
Here is an article on iPhone app rating popup. http://mobileorchard.com/fighting-back-against-the-app-stores-negative-rating-bias/
Nothing really new here - ask every 10 days in the beginning, ask every month when your app is established. I am thinking on showing the popup on 3rd load at first, then every 10 days and hopefully the time will come when we will show it just once a month.
Common practice is to show popup upon loading, we should be able to cover both signed in and not signed in users in case if the app requires sign in for limited actions.
I am aware of 2 patterns:
Pattern 1:
Like this app? Please rate it in AppStore.
[No, thanks] [Rate It!]
Pattern 2:
Like this app? Please rate it in AppStore.
[Rate It!]
[Later]
[No, thanks]