How to add a CollectionView to a ViewController - ios

Question

I want to add a CollectionView inside my ViewController using the same code that I have on a CollectionViewController.
CollectionViewController.m
#interface StoreViewController ()
#property (readwrite, nonatomic, strong) NSArray *latestProducts;
#end
#implementation StoreViewController
- (void)setLatestProducts:(NSArray *)latestProducts {
_latestProducts = latestProducts;
[self.collectionView reloadData];
}
- (Product *)releaseForIndexPath:(NSIndexPath *)indexPath {
return [self.latestProducts objectAtIndex:indexPath.row];
}
- (void)loadData:(id)sender {
[self showLoadingView];
[Product latestProductsWithBlock:^(NSArray *products, NSError *error) {
self.latestProducts = products;
dispatch_async(dispatch_get_main_queue(), ^{
[self hideLoadingView];
});
if (error) {
[[[UIAlertView alloc] initWithTitle:[error localizedDescription] message:[error localizedFailureReason] delegate:nil cancelButtonTitle:NSLocalizedString(#"OK", nil) otherButtonTitles:nil, nil] show];
}
}];
}
#pragma mark - UIViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.navigationItem.title = NSLocalizedString(#"Deadstock", nil);
[self.collectionView registerClass:[ProductCell class] forCellWithReuseIdentifier:#"ProductCell"];
[self loadData:nil];
}
#pragma mark - UICollectionViewDelegate
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return [self.latestProducts count];
}
#pragma mark - Collection View Cell
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
static NSString *identifier = #"productCell";
ProductCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.product = [self releaseForIndexPath:indexPath];
return cell;
}
#end
ProductCell.m
#implementation ProductCell
- (void)setProduct:(Product *)product {
_product = product;
dispatch_async(dispatch_get_main_queue(), ^{
[self.image setImageWithURL:self.product.thumbnailImageURL];
});
self.image.clipsToBounds = YES;
}
#end
I have an NSObject that parses my cell's content, from my database.
Product.h
#interface Product : NSObject
#property (readonly) NSURL *thumbnailImageURL;
- (instancetype)initWithAttributes:(NSDictionary *)attributes;
+ (void)latestProductsWithBlock:(void (^)(NSArray *products, NSError *error))block;
#end
Following a tutorial I fount online, I created a NSObject file ("ProductDataSource") and on my Storyboard I added an Object to my ViewController and linked it to my CollectionView. I copied the code from my CollectionViewController to ProductDataSource but it's not creating my cells. If I set the numberOfItemsInSection to a number it created the cells but not when I change the code to return [self.latestProducts count]. It might have something to do with "loadData" section I have on my CollectionViewController, since ProductDataSource doesn't have a viewDidLoad method.
- (void)loadData:(id)sender {
[self showLoadingView];
[Product latestProductsWithBlock:^(NSArray *products, NSError *error) {
self.latestProducts = products;
dispatch_async(dispatch_get_main_queue(), ^{
[self hideLoadingView];
});
if (error) {
[[[UIAlertView alloc] initWithTitle:[error localizedDescription] message:[error localizedFailureReason] delegate:nil cancelButtonTitle:NSLocalizedString(#"OK", nil) otherButtonTitles:nil, nil] show];
}
}];
}
#pragma mark - UIViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.navigationItem.title = NSLocalizedString(#"Deadstock", nil);
[self.collectionView registerClass:[ProductCell class] forCellWithReuseIdentifier:#"ProductCell"];
[self loadData:nil];
}
Any help? Thanks.

Answer 1

You have to reload the collection view after you get latestProducts. Try to put [self.collectionView reloadData] after [self hideLoadingView];

Answer 2

Put a breakpoint in your cellForItemAtIndexPath method to ensure that method is being hit. If it doesn't get hit, that means you need to set your collection view's datasource.

Answer 3

So if I am understanding correctly, you have an existing UICollectionViewController called CollectionViewController and want to reuse the logic in another UIViewController.
a UICollectionViewController is essentially a UIViewController that has a UICollectionView subview and conforms to the UICollectionViewDataSource and UICollectionViewDelegate protocols.
In order to embed a UICollectionView into your UIViewController, you need to create Delegate and DataSource classes for your CollectionView and assign them in the UIViewController.
There are some good code examples here: UICollectionView with UIViewController As Data Source
GitHub Repo with a small single page app using a CollectionView inside a UIViewController:
https://github.com/pnavk/CollectionViewSample