CODEWITHSUNDEEP
iosobjective-c
Chas Burks
Chas Burks

Reputation: 47

UICollectionView does not stay selected after scrolling

When I select a cell, it turns blue, which is good. Then when I scroll up and the cell out of view, it turns back to original color. Not sure how to fix this.

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath];
    cell.backgroundColor=[UIColor lightGrayColor];
    [collectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];
    self.collectionView.allowsMultipleSelection=YES;

    return cell;
}

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *datasetCell =[collectionView cellForItemAtIndexPath:indexPath];
    datasetCell.backgroundColor = [UIColor blueColor];  
}

-(void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *datasetCell =[collectionView cellForItemAtIndexPath:indexPath];  
}

Upvotes: 3

Views: 1442

Answers (2)

insys
insys

Reputation: 1288

In your first method, you are practically telling the collection view to select any cell that it asks for. Instead, you should check whether the cell you return has the same path as the selected one, and only then give it color:

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath];
    if ([indexPath isEqual:self.selectedIndexPath]) // you need to create selectedIndexPath as a property
    {
        cell.backgroundColor=[UIColor blueColor];
    }
    else
    {
        cell.backgroundColor=[UIColor lightGrayColor];
    }
    return cell;
}

And then:

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath 
{
    self.selectedIndexPath = indexPath;
}

Upvotes: 3

Max
Max

Reputation: 3429

When cell are reused, the selection state is lost. So you need to save the indexPath of the selection in didSelectItemAtIndexPath. And when you dequeue the cell you need to check and restore the state

Upvotes: 2

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