trigger rating and review screen using SKStoreReviewController

RateApp.swift

//
//  RateApp.swift
//  https://medium.com/@dejanatanasov
//

import Foundation
import StoreKit

class RateApp {

    static let numberOfLaunches = 5 /* set number of app launches */

    /* increments the total number of app launches */
    class func incrementAppRuns() {
        let runs = getRunCounts() + 1
        UserDefaults.standard.set(runs, forKey: "RATE_NUMBER_OF_RUNS")
        UserDefaults.standard.synchronize()
    }
    
    /* fetches the total number of app launches */
    class func getRunCounts() -> Int {
        if let runs = UserDefaults.standard.value(forKey: "RATE_NUMBER_OF_RUNS") as? Int{
            return runs
        }
        return 0
    }
    
    /* checks whether the rating and review screen should be shown or not */
    class func canShowReview() -> Bool{
        let runs = getRunCounts()
        return runs == numberOfLaunches
    }
    
    /* request the rating and review screen to be shown to the user (if condition is satisfied)   */
    class func showReview(){
        if #available(iOS 10.3, *) {
            if canShowReview() {
                SKStoreReviewController.requestReview()
            }
        }
    }
}