Push notification flag in Settings

When a app has a push notification feature implemented at what point in time do we see the app name under Settings-->Notifications for enabling/disabling notifications?

Is it when you install the app and IOS will automatically come to know this or we need to run the app at-least once to see this option.

I am seeing two different cases: When I install the app on my iPod touch I immediately see the Push notification enabling switch in Settings but when I install 开发者_StackOverflow中文版it on my iPhone it do not show this option even after running the app. What could be the reason?

It shows when you register the app for push notifications in code. The reason it is showing up for you as soon as you install it on one of your devices is that you have already accepted it on a previous install of the same app, and uninstalling/reinstalling unfortunately does not cause iOS to forget this.