UICollectionViewCell: Add a view in cell on tap - objective-c

Question

I have a uicollectionview and I am trying to add a a view to the collectionview cell when it is tapped.
Here is the code I have tried to implement
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
WeekCell *cell = (WeekCell*)[collectionView cellForItemAtIndexPath:indexPath];
NSLog(#"%#", cell.descLabel.text);
UIView *view = [[UIView alloc]initWithFrame:cell.backgroundView.bounds];
UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(10, 10, 40, 40)];
label.text = #"new label";
[view addSubview:labels];
view.backgroundColor = [UIColor whiteColor];
[cell.backgroundView addSubview:view];
}
Here WeekCell is a custom UICollectionViewCell with a property view , backgroundview. You will also notice an NSLog in the code. This verifies that the correct cell is being retrieved. What is not working is according to the code, the text should change to white with a new UILabel but this is not the case. The cell's appearance does not change.
EDIT
As suggested I have tried to directly modify the model and call the reloadItemsAtIndexPaths to reload the data. I get an issue where the the "tapped behaviour" is being copied on to untapped cells.
Here is the new code:
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
if([[modelArray objectAtIndex:indexPath.row] isEqualToString:#"1"]){
cell.overviewView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:imageString]];
}else{
cell.overviewView.alpha = 0;
}
}
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
WeekCell *cell = (WeekCell*)[collectionView cellForItemAtIndexPath:indexPath];
NSLog(#"%#", cell.descLabel.text);
if([[modelArray objectAtIndex:indexPath.row] isEqualToString:#"1"]){
[modelArray setObject:#"0" atIndexedSubscript:indexPath.row];
}else{
[modelArray setObject:#"1" atIndexedSubscript:indexPath.row];
}
NSLog(#"sequence : %#", modelArray);
[collectionView reloadItemsAtIndexPaths:#[indexPath]];
}
What I am doing is changing the alpha value of the view in the tapped cell to 0. This causes the other cells at random order to disappear once I scroll.

Answer 1

Instead of:
[cell.backgroundView addSubview:view];
... add to content view:
[cell.contentView addSubview:view];
Remarks:
Direct manipulation on collection view cell can cause unexpected results. For instance if cell gets reused. Better to update the model that gets rendered by the cell and call reloadItemsAtIndexPaths: that will automatically(internally) call collectionView:cellForItemAtIndexPath: which should configure(or invoke configuration routine) for the cell that can adjust its presentation.
UPDATE:
You should reset alpha of cells that should be visible, bellow is collectionView:cellForItemAtIndexPath: method with correction:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
if([[modelArray objectAtIndex:indexPath.row] isEqualToString:#"1"]){
cell.overviewView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:imageString]];
cell.overviewView.alpha = 1;
} else {
cell.overviewView.alpha = 0;
}
}

Answer 2

The backgroundView property of a UICollectionViewCell is placed behind the content view. So the reason for the label not being visible could be because it is masked by the content view.
You could set clearColor for the Content view views or add the new view to the contentView;
[cell.contentView addSubview:view];
Hope this information is helpful.