Sample of a CollectionViewController with 3 sections

CollectionViewController.m

@property (nonatomic, strong) NSArray *sections;

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Cell Sections in Array
    self.sections = @[
                      @{@"identifier": @"firstCell"},
                      @{@"identifier": @"secondCell"},
                      @{@"identifier": @"thirdCell"},
                     ];
}

#pragma mark -
#pragma mark UICollectionViewDataSource

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 1;
}

-(NSInteger)collectionView:(UICollectionView *)collectionView
    numberOfItemsInSection:(NSInteger)section
{
    return self.sections.count;
}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    id object = self.sections[indexPath.row];
    
    UICollectionViewCell *cell = [collectionView
                                  dequeueReusableCellWithReuseIdentifier:object[@"identifier"]
                                  forIndexPath:indexPath];
    
    return cell;
}