iOS 6 CollectionView Dynamically change Layout - ios

Question

I'm kinda newbie in UICollectionView and I'm working in a project that dynamically changes the UICollectionViewLayout in a given action.
My CollectionView has 6 sections, each of them with 10 elements. Those Cells are basically an UIImageView and my Custom Layout called StackViewLayout stacks all elements for each section (something like Apple's Photos.app).
If the user selects the element of the stack (for all sections), the UICollectionView dynamically changes the layout to the UICollectionViewFlowLayout, so all the elements can be viewed as grid.
My problem is that when user selects a stack, no matter which section, when the Layout is changed do Flow Layout, all sections are displayed in the grid, instead of displaying the elements for the selected section (stack), which is the behavior I wanted.
Is there any way to show only the Flow Layout for the selected section in the Custom Layout?
Here is my Controller Implementation snippet code:
- (void)viewDidLoad
{
[super viewDidLoad];
[self loadStackLayout]; // stack all sections at first load.
}
#pragma mark - UICollectionView Data Source Methods
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
return 6;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return 10;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath;
{
// custom UICollectionViewCell, which will hold an image.
CVCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"MyCell" forIndexPath:indexPath];
cell.imageView.image = _images[indexPath.row];
return cell;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
// element size.
return CGSizeMake(100,100);
}
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
if (isStacked)
{
[self loadFlowLayout]; //HERE I WANT TO LOAD FLOW LAYOUT ONLY FOR THE SECTION OF THE SELECTED ITEM!
} else
{
// to implement.
}
}
// HERE IS THE METHOD THAT CALLS MY CUSTOM LAYOUT IN ORDER TO STACK THE ELEMENTS FOR EACH SECTION IN COLLECTION VIEW. IT IS WORKING AS IT SHOULD.
-(void)loadStackLayout
{
if (([self.collectionView.collectionViewLayout isKindOfClass:[UICollectionViewFlowLayout class]]))
{
isStacked = YES;
[self.collectionView setCollectionViewLayout:[[StackViewLayout alloc] init] animated:YES];
}
}
// HERE IS THE METHOD THAT CALLS MY FLOWLAYOUT IN ORDER TO UN-STACK THE ELEMENTS AND SHOW THEM IN A GRID. CURRENTLY IT IS SHOWING ALL SECTIONS IN THE GRID.
-(void)loadFlowLayout
{
if (([self.collectionView.collectionViewLayout isKindOfClass:[StackViewLayout class]]))
{
isStacked = NO;
[self.collectionView setCollectionViewLayout:[[UICollectionViewFlowLayout alloc] init] animated:YES];
}
}

Answer 1

I think you can probably do it by having an if clause in your numberOfItemsInSection: method, to return 0 for any section that's not the selected one. Obviously, you'll need to keep track of the selected section to do this.