As you may have seen in some apps an alert pops up asking the user to rate the app in itunes and usually the alternatives you get to choose from is something like: Sure which opens the rate page for the app. The second option is No Thanks which closes the alert and the third option usually is maybe later which displays the alert later.
I was wondering how to do this. I want the alert to be displayed after say the app has launched 20 times if that would be possible. And how can I create an maybe later alternative which displays the alert maybe 15 launches of the app later?
And a final question is there a special link for the apps rate page? So when you click the sure button or whatever it will take your directly to the rate page.
Check out my answer for this similar question. I provide two different links you can use for taking the user to the "rate this app" screen in the App Store.
I've used this: https://github.com/arashpayan/appirater. You can look at my fork as well for a specific mod I needed.
[EDIT: comment re NSUserDefaults]
I suggested this link because it is a full, working implementation of what you describe that is easily integrated into existing apps. I've used (and modified) it myself. NSUserDefaults is a general purpose mechanism for persisting app state. I agree with the others that it's a very useful thing to learn and use, it's just not a full answer to your question. If you choose to roll your own implementation of a rating system (nothing wrong with that) you will most likely use NSUserDefaults to store the relevant info.
You can use NSUserDefaults to save the launch count (increment it in application:didFinishLaunchingWithOptions:), then save the user's choice another preference key. If the user says later, you could reset the counter back to zero.
I don't think there is a special rating link, but you can link to your app's specific App Store page. This was incorrect, as TomSwift points out; see Direct "rate in iTunes" link in my app?
I wrote a library for doing this with minimal effort on your part:
https://github.com/nicklockwood/iRate
I'd recommend using a library rather than rolling your own solution. It may seem like a simple problem but the library takes care of a whole bunch of extra stuff, like ensuring that the user is prompted for each new installed version, that they are reminded after a certain time if they decline, that they aren't prompted to go to the app store unless they have a network connection, etc.
来源：https://stackoverflow.com/questions/5639619/alert-for-reminding-the-user-to-rate-the-app