Appending core data object into an array

Question

I want to append json object I save in core data into an array, but it's not working with append. how I can append core data object into an array.

this is my array

private var videos = [Video]()

this my function to fetch an api and store the json into core data

let params = ["part": "snippet", "q": "tausiyah \(name)", "key": "AIzaSyC2mn0PTL8JmSWEthvksdJLvsnwo5Tu9BA"]

        APIServices.shared.fetchData(url: APIServices.youtubeBaseURL, params: params, of: Item.self) { (items) in
            items.forEach({ (item) in
                print(item.id.videoId)
                let privateContext = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
                privateContext.parent = CoreDataManager.shared.persistenceContainer.viewContext

                let video = Video(context: privateContext)
                video.title = item.snippet.title
                video.videoId = item.id.videoId

                do {
                    try privateContext.save()
                    try privateContext.parent?.save()
                    self.videos.append(video) // this is I can't append core data into my array
                } catch let saveErr {
                    print("Failed to save json data:", saveErr)
                }
            })
            DispatchQueue.main.async {
                self.collectionView.reloadData()
            }
        }

The fetch data will execute asynchronously. You need the DispatchQueue.main.async inside the fetch data closure. — Paulw11
– Paulw11, Commented Dec 18, 2018 at 11:15
@Paulw11 what do you mean? I need to add dispatch again so my append will work? — ferryawijayanto
– ferryawijayanto, Commented Dec 18, 2018 at 11:19
Sorry, I misread your }. What do you mean by "not working" and "I can't append...". What happens? Do you get an error message? — Paulw11
– Paulw11, Commented Dec 18, 2018 at 11:23
What do you see if you print the array.count after the append? It still looks like an asynchronous problem to me. Also show your numberOfItems(in section:) code — Paulw11
– Paulw11, Commented Dec 18, 2018 at 11:38

A. Amini · Accepted Answer · 2018-12-18 14:12:38Z

1

try this and see the result:

private var videos = [Video]() {
   didSet {
      print("AAA: \(videos.last().title)")
      DispatchQueue.main.async {
          self.collectionView.reloadData()
      }
   }
}

be sure that you have set numberOfItems & Section to you array.count

answered Dec 18, 2018 at 14:12

A. Amini

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