CODEWITHSUNDEEP
iosswiftuicollectionviewcellindexpath
Rohan Vasishth
Rohan Vasishth

Reputation: 417

ERROR: Attempt to insert item 0 into section 0, but there are only 0 items in section 0 after the update

My code:

    DataService.dataService.fetchDataFromServer { (channel) in
        self.channels.append(channel)
        let indexPath = IndexPath(item: self.channels.count - 1, section: 0)
        self.collectionView?.insertItems(at: [indexPath])
    }

Fetch Data From Server Function:

 func fetchDataFromServer(callBack: @escaping (Channel) -> ()) {
        DataService.dataService.CHANNEL_REF.observe(.childAdded, with: { (snapshot) in
            let channel = Channel(key: snapshot.key, snapshot: snapshot.value as! Dictionary<String, AnyObject>)
            callBack(channel)
        })
    }

Number of Items Section:

override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    // #warning Incomplete implementation, return the number of items
    return 0
}

The Full Error:

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'attempt to insert item 0 into section 0, but there are only 0 items in section 0 after the update'

I am working with a collection view and have no clue why this error is showing up.

Any help would be appreciated!

Upvotes: 1

Views: 10523

Answers (4)

Almog C
Almog C

Reputation: 895

For other users stumbling upon this question, these errors also arise when trying to update a TableView or CollectionView with no dataSource assigned. Make sure the TableView's dataSource is connected (when using a storyboard or nib) or assigned programmatically.

Upvotes: 2

Deo Kalule
Deo Kalule

Reputation: 15

Make sure you connected the datasource, that was something that tripped me up because its so basic and sometime you don't think about it.

Upvotes: 1

Laura Corssac
Laura Corssac

Reputation: 1377

I was having the same problem and fixed putting [unowned self] in the closure and forcing UI updates to be done on main thread. Also, as the others have said, the numberOfItemsInSection method should return the number of items in your array. Here is my final code:

DataManager.fetchDish() { [unowned self] dish in
        if let dish = dish {
            DispatchQueue.main.async {
                self.dishes.append(dish)
                self.dishesCollectionView.insertItems(at: [IndexPath(row: self.dishes.count - 1, section: 0)])
            }
        }
    }

Upvotes: 4

Paulw11
Paulw11

Reputation: 114975

Your numberOfItemsInSection is returning 0, so when tell the collection view you are adding an item, it gets upset when this method says that there are still 0 items in the collection.

Your code even has a comment // #warning Incomplete implementation, return the number of items

You probably want something like:

override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    return self.channels.count
}

Upvotes: 5

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