StoreReviewHelper.swift

//
//  StoreReviewHelper.swift
//  Template1
//
//  Created by Apple on 14/11/17.
//  Copyright © 2017 Mobiotics. All rights reserved.
//

import Foundation
import StoreKit

struct StoreReviewHelper {
    static func incrementAppOpenedCount() { // called from appdelegate didfinishLaunchingWithOptions:
        guard var appOpenCount = Defaults.value(forKey: UserDefaultsKeys.APP_OPENED_COUNT) as? Int else {
            Defaults.set(1, forKey: UserDefaultsKeys.APP_OPENED_COUNT)
            return
        }
        appOpenCount += 1
        Defaults.set(appOpenCount, forKey: UserDefaultsKeys.APP_OPENED_COUNT)
    }
    static func checkAndAskForReview() { // call this whenever appropriate
        // this will not be shown everytime. Apple has some internal logic on how to show this.
        guard var appOpenCount = Defaults.value(forKey: UserDefaultsKeys.APP_OPENED_COUNT) as? Int else {
            Defaults.set(1, forKey: UserDefaultsKeys.APP_OPENED_COUNT)
            return
        }
        
        switch appOpenCount {
        case 10,50:
            StoreReviewHelper().requestReview()
        case _ where appOpenCount%100 == 0 :
            StoreReviewHelper().requestReview()
        default:
            print("App run count is : \(appOpenCount)")
            break;
        }
        
    }
    fileprivate func requestReview() {
        if #available(iOS 10.3, *) {
            SKStoreReviewController.requestReview()
        } else {
            // Fallback on earlier versions
            // Try any other 3rd party or manual method here.
        }
    }
}

how to implement this to the mainviewcontroller ?

Use of unresolved identifier 'UserDefaultsKeys'
Use of unresolved identifier 'Defaults'
any idea why xcode 9.2 does not reconigze this

I found from another page, that it's just a struct.

import Foundation

struct UserDefaultsKeys {
    // Reviews
    static let lastVersionPromptedForReviewKey = "LAST_VERSION_PROMOTED_FOR_REVIEW"
    
    // Counts
    static let appLaunchCountKey = "APP_OPENED_COUNT"
}

Full code:
https://medium.com/@abhimuralidharan/asking-customers-for-ratings-and-reviews-from-inside-the-app-in-ios-d85f256dd4ef

Is there a license for this file? Thanks!