UICollectionView didDeselectItemAtIndexPath不获取单元格

Question

I have a simple collectionView, and with didSelectItemAtIndexPath and didDeselectItemAtIndexPath I change cell's background color.

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

- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath{
    UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
    cell.contentView.backgroundColor = [UIColor clearColor];
}

All works fine, but if I select a cell, scroll the list (my selected cell go out of screen) and I select another, in didDeselectItemAtIndexPath my "cell" variable is nil. Why?

NB: only when the selected cell go out of screen

Answer 1

Simply logic behind cell selected and deselected in proper way:

ViewController.h

 int selectedIndex;

ViewController.m

- (void)viewDidLoad 
{
      [super viewDidLoad];
      selectedIndex = -1;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
  {
        static NSString *identifier = @"CollectionCell";
        WalletCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

        if(indexPath.row == selectedIndex)
        {
               cell.selected = YES;
               cell.backgroundColor = [UIColor redColor];
        }
        else
        {
               cell.selected = NO;
               cell.backgroundColor = [UIColor clearColor];
        }
          return cell;
  }


- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
     UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
      selectedIndex = (int)indexPath.row;
       cell.backgroundColor = [UIColor redColor];
}

 - (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath
 {
       UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
       cell.backgroundColor = [UIColor clearColor];
 }