Frustrating memory leak when loading an interstitial ad in Swift - ios

Question

I am dealing with an infuriating memory leak in regards to loading an interstitial ad via AdMob. When observing the memory in Xcode & Instruments, the memory jumps 10 MB every time I visit the view controller hosting the ad. Also when closing the app on my phone and reopening it, causes the memory to jump 30-40 mb as well which is just ridiculous.
I have tried profiling this in Instruments and the memory being allocated are all system libraries and nothing that points out to what is wrong. I have read other Stack Overflow answers such as ADMOB Memory Leaking?
but no answer has helped me so far. Maybe somebody can tell me what is wrong with my code? I have followed the exact documentation AdMob provides which is https://developers.google.com/admob/ios/interstitial and all works fine except this crazy memory leak. Here is the exact code that is causing the leak below.
class ViewController: UIViewController, GADInterstitialDelegate {
var interstitial: GADInterstitial!
override func viewDidLoad() {
interstitial = createAndLoadInterstitial()
interstitial.delegate = self
}
func update() {
if interstitial.isReady {
interstitial.present(fromRootViewController: self)
}
}
func createAndLoadInterstitial() -> GADInterstitial {
let interstitial = GADInterstitial(adUnitID: "ca-app-pub-3940256099942544/4411468910")
interstitial.delegate = self
let request = GADRequest()
interstitial.load(request)
return interstitial
}
func interstitialDidDismissScreen(_ ad: GADInterstitial) {
interstitial = createAndLoadInterstitial()
}
// I am calling update() inside a button when pressed in this VC.

Answer 1

I just want to say that this actually has been solved by me. I did as one of the above stated in the comments. I took my code that was on the view controller hosting the interstitial ad and moved it to the app delegate. I simply then just referenced the interstitial ad object whenever I need it in my project. This brought the memory back down to whatever it allocated upon visiting the controller hosting the ad. For those that want to see a very simple example of what this looks like in the app delegate:
import UIKit
import GoogleMobileAds
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, GADInterstitialDelegate {
var myInterstitial: GADInterstitial!
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
GADMobileAds.sharedInstance().start(completionHandler: nil)
myInterstitial = createAndLoadInterstitial()
return true
}
func createAndLoadInterstitial() -> GADInterstitial {
let interstitial = GADInterstitial(adUnitID: "yourAdID")
interstitial.delegate = self
let request = GADRequest()
interstitial.load(request)
return interstitial
}
func interstitialDidDismissScreen(_ ad: GADInterstitial) {
myInterstitial = createAndLoadInterstitial()
}

Answer 2

I also had this issue and turns out I just needed a pod update.
In version 7.53.0 the update included 'Fixed the GADBlockSignalSource memory leak that occurred when loading ads' which may relate to the interstitial memory leak issue we were experiencing.
Release notes:
https://developers.google.com/admob/ios/rel-notes