Just for fun, another approach would be to just leave the paging and horizontal scrolling set, add a method that changes the order of the array items to convert from 'top to bottom, left to right' to visually 'left to right, top to bottom' and fill the in-between cells with empty hidden cells to make the spacing right. In case of 7 items in a grid of 9, this would go like this:
[1][4][7]
[2][5][ ]
[3][6][ ]
should become
[1][2][3]
[4][5][6]
[7][ ][ ]
so 1=1, 2=4, 3=7 etc. and 6=empty. You can reorder them by calculating the total number of rows and columns, then calculate the row and column number for each cell, change the row for the column and vice versa and then you have the new indexes. When the cell doesn't have a value corresponding to the image you can return an empty cell and set cell.hidden = YES; to it.
It works quite well in a soundboard app I built, so if anyone would like working code I'll add it. Only little code is required to make this trick work, it sounds harder than it is!
Update
I doubt this is the best solution, but by request here's working code:
- (void)viewDidLoad {
// Fill an `NSArray` with items in normal order
items = [NSMutableArray arrayWithObjects:
[NSDictionary dictionaryWithObjectsAndKeys:@"Some label 1", @"label", @"Some value 1", @"value", nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Some label 2", @"label", @"Some value 2", @"value", nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Some label 3", @"label", @"Some value 3", @"value", nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Some label 4", @"label", @"Some value 4", @"value", nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Some label 5", @"label", @"Some value 5", @"value", nil],
nil
];
// Calculate number of rows and columns based on width and height of the `UICollectionView` and individual cells (you might have to add margins to the equation based on your setup!)
CGFloat w = myCollectionView.frame.size.width;
CGFloat h = myCollectionView.frame.size.height;
rows = floor(h / cellHeight);
columns = floor(w / cellWidth);
}
// Calculate number of sections
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return ceil((float)items.count / (float)(rows * columns));
}
// Every section has to have every cell filled, as we need to add empty cells as well to correct the spacing
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return rows*columns;
}
// And now the most important one
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier@"myIdentifier" forIndexPath:indexPath];
// Convert rows and columns
int row = indexPath.row % rows;
int col = floor(indexPath.row / rows);
// Calculate the new index in the `NSArray`
int newIndex = ((int)indexPath.section * rows * columns) + col + row * columns;
// If the newIndex is within the range of the items array we show the cell, if not we hide it
if(newIndex < items.count) {
NSDictionary *item = [items objectAtIndex:newIndex];
cell.label.text = [item objectForKey:@"label"];
cell.hidden = NO;
} else {
cell.hidden = YES;
}
return cell;
}
If you'd like to use the didSelectItemAtIndexPath method you have to use the same conversion that is used in cellForItemAtIndexPath to get the corresponding item. If you have cell margins you need to add them to the rows and columns calculation, as those have to be correct in order for this to work.
