UICollectionViewCell willAppear not being called - objective-c

Question

I'm trying to do a UICollectionView of articles that doesn't eats RAM like an elephant. So, the UICollectionView consists of full screen cells that contain one image. If the UICollectionViewCell appears, the content gets loaded in. This is the code:
- (void)viewDidLoad {
UICollectionViewFlowLayout *layout=[[UICollectionViewFlowLayout alloc] init];
layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
layout.itemSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
layout.minimumInteritemSpacing = 0;
layout.minimumLineSpacing = 0;
_collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:layout];
[_collectionView setDataSource:self];
[_collectionView setDelegate:self];
_collectionView.pagingEnabled = YES;
[_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:#"cellIdentifier"];
[_collectionView setBackgroundColor:[UIColor redColor]];
[self.view addSubview:_collectionView];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"cellIdentifier" forIndexPath:indexPath];
//add UIImageView here
//add UITextView with tag 123 here
return cell;
}
- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [_collectionView cellForItemAtIndexPath:indexPath];
UITextView *textView = [cell viewWithTag:123];
textView.text = #"Testing this out.";
}
However, this doesn't do anything. No errors are thrown, it just doesn't do anything. What am I doing wrong?