Count is performed before data is loaded

[ArvinDaCoda]

Hi,

I have implemented collectionview a similar way, but are having issues when getting the data from and external database (Google Firebase). The function that counts the collectionview cells are performed before the data is stored in the episodesArray.

I guess I have to perform some delay or run the functions in the same thread, but are pretty newbie at this, so any help is much appreciated. THANKS!!!!

I have separated the code into 2 swift files:

1. UIViewController.swift

---

... func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: "Cell") as! EpisodesRow cell.categoryID = "siibMVy0vuiXPVW2IZsz" //Temp static solution for testing cell.getEpisodes() return cell } ...

2. CategoryRow.swift

---

... //Connect to Firebase and Datamodel let db = Firestore.firestore() var episodesArray : [Episodes] = Episodes

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { print("Count: (episodesArray.count)") return episodesArray.count }

func getEpisodes() { //print(categoryID) db.collection("Episodes").whereField("EpisodeCatID", isEqualTo: categoryID).getDocuments { (snapshot, error) in if error != nil { //error handling print(error!) } else { //Success for document in (snapshot?.documents)! { let episodeData = Episodes() episodeData.EpisodeName = (document.data()["EpisodeName"] as? String)! episodeData.EpisodeImage = (document.data()["EpisodeImage"] as? String)! self.episodesArray.append(episodeData)

                print(" \(self.episodesArray.count)")
                print(" \(self.episodesArray)")
            }
        }
    }
}

...

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[johncpang]

I notice one thing: you put the network code inside the (reusable) table view cell. The view cell can be reused or disposed when scrolling. Therefore, it is not proper way. Instead, the network code shall be put inside view controller, which is a singleton (compare to those table view cells) until users dismiss it.

In your view controller, put up the code to get data. If you prefer to delay the loading till the table view cell appears (thus the collection view is displayed), then you'll need a way to remember if that row is loaded, loading or load failed. When you've got your data ready (or updated), you shall call self.tableView.reloadData().

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell") as! EpisodesRow
    cell.categoryID = "siibMVy0vuiXPVW2IZsz" //Temp static solution for testing
    if (!self.hasLoaded[cell.categoryID]) {
        self.getEpisodes(cell.categoryID)  // Lazy downloading
    }
    cell.collectionView.reloadData()
    return cell
}

Then implement the datasource and delegate functions for collection view inside view controller as usual.