I am developing an Android App. In which everything is working right. My app is ready to launch. But there I need to implement one more feature. I need to display a popup wh
As you see from the other post you have linked, there isn't a way for the app to know if the user has left a review or not. And for good reason.
Think about it, if an app could tell if the user has left a review or not, the developer could restrict certain features that would only be unlocked if the user leaves a 5/5 rating. This would lead the other users of Google Play to not trust the reviews and would undermine the rating system.
The alternative solutions I have seen is that the app reminds the user to submit a rating whenever the app is opened a specific number of times, or a set interval. For example, on every 10th time the app is opened, ask the user to leave a rating and provide a "already done" and "remind me later" button. Keep showing this message if the user has chosen to remind him/her later. Some other apps developers show this message with an increasing interval (like, 5, 10, 15nth time the app is opened), because if a user hasn't left a review on the, for example, 100th time the app was opened, it's probably likely s/he won't be leaving one.
This solution isn't perfect, but I think it's the best you have for now. It does lead you to trust the user, but realize that the alternative would mean a potentially worse experience for everyone in the app market.