Ads array in tableview out of index - arrays

Question

I have 3 arrays of data. I want to show ads after every 5 user cells in the table.
var nativeAds = [GADNativeAd]()
var item = [NewsElement]()
var filterItem = [NewsElement]()
After displaying 5 cells with ads, the application crashes with an error "Thread 1: Fatal error: Index out of range"
How do I re-add ads to the array or select an array with ads again?
There are smart guys sitting here, please help me. Thank you in advance!
below is my code
extension NewsViewController: GADNativeAdLoaderDelegate {
func adLoader(_ adLoader: GADAdLoader, didFailToReceiveAdWithError error: Error) {
print("\(adLoader) failed with error: \(error.localizedDescription)")
}
func adLoader(_ adLoader: GADAdLoader, didReceive nativeAd: GADNativeAd) {
print("Received native ad: \(nativeAd)")
nativeAds.append(nativeAd)
}
func adLoaderDidFinishLoading(_ adLoader: GADAdLoader) {
newsTblView.reloadData()
}
}
extension NewsViewController: UITableViewDelegate, UITableViewDataSource {
private func dataRow(for indexPath: IndexPath) -> Int? {
let (quotient, remainder) = (indexPath.row + 1).quotientAndRemainder(dividingBy: numAdsToLoad)
if remainder == 0 { return nil }
return quotient * (numAdsToLoad - 1) + remainder - 1
}
private func adRow(for indexPath: IndexPath) -> Int? {
let (quotient, remainder) = (indexPath.row + 1).quotientAndRemainder(dividingBy: numAdsToLoad)
if remainder != 0 { return nil }
return quotient - 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if searchActive {
return filterItem.count
} else {
return item.count + nativeAds.count
}
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if let row = dataRow(for: indexPath) {
let cell = tableView.dequeueReusableCell(withIdentifier: "NewsTableViewCell", for: indexPath) as! NewsTableViewCell
if searchActive {
let items = filterItem[row]
cell.configCell(model: items )
} else {
let items = item[row]
cell.configCell(model: items )
}
cell.selectionStyle = .none
cell.backgroundColor = .clear
return cell
} else if let row = adRow(for: indexPath) {
let nativeAd = nativeAds[row] <-- "Thread 1: Fatal error: Index out of range"
nativeAd.rootViewController = self
let nativeAdCell = tableView.dequeueReusableCell(withIdentifier: "UnifiedNativeAdCell", for: indexPath) as! GADNativeAdViewCell
nativeAdCell.setAdData()
return nativeAdCell
}
fatalError("Did not find data or ad for cell: Should never get here")
}
}