Replacing Not adding: UICollectionView - iphone

Question

I am creating a client app for Instagram the gets pictures, however when the user gets to the bottom of the page it is is supposed to bring a new group of uicollectionviewcell's however it replaces the existing ones and i cannot see them anymore unless i refresh. All the nessecary code is provided below, thanks for your help in advance:
#interface StreamViewController () <UITextFieldDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout>
#property (nonatomic, strong) NSMutableDictionary *timelineResponse;
#property (nonatomic, strong) CredentialStore *credentialStore;
#property (weak, nonatomic) IBOutlet UICollectionView *collectionView;
#end
#implementation StreamViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self refreshInstagram];
//Refresh
UIRefreshControl *refreshControl = [[UIRefreshControl alloc] init];
[refreshControl addTarget:self action:#selector(startRefresh:)
forControlEvents:UIControlEventValueChanged];
[self.collectionView addSubview:refreshControl];
//Instigate Navigation Bar Buttons
UIButton *barButton = [UIButton buttonWithType:UIButtonTypeCustom];
[barButton setTitle:#"" forState:UIControlStateNormal];
[barButton setBackgroundImage:[UIImage imageNamed:#"barButton.png"] forState:UIControlStateNormal];
[barButton setBackgroundImage:[UIImage imageNamed:#"barButton_s.png"] forState:UIControlStateHighlighted];
[barButton addTarget:self action:#selector(didTapBarButton:) forControlEvents:UIControlEventTouchUpInside];
barButton.frame = CGRectMake(0.0f, 0.0f, 30.0f, 30.0f);
UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithCustomView:barButton];
self.navBar.leftBarButtonItem = barButtonItem;
UIButton *postButton = [UIButton buttonWithType:UIButtonTypeCustom];
[postButton setTitle:#"" forState:UIControlStateNormal];
[postButton setBackgroundImage:[UIImage imageNamed:#"pen_usIMG.png"] forState:UIControlStateNormal];
[postButton setBackgroundImage:[UIImage imageNamed:#"pen_sIMG.png"] forState:UIControlStateHighlighted];
[postButton addTarget:self action:#selector(didTapPostButton:) forControlEvents:UIControlEventTouchUpInside];
postButton.frame = CGRectMake(0.0f, 0.0f, 30.0f, 30.0f);
UIBarButtonItem *postButtonItem = [[UIBarButtonItem alloc] initWithCustomView:postButton];
self.navBar.rightBarButtonItem = postButtonItem;
//Reload by default
[self.collectionView reloadData];
}
//Global refresh Instagram Method
- (void)refreshInstagram {
[[InstagramClient sharedClient] getPath:#"users/self/feed"
parameters:nil
success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"Response: %#", responseObject);
self.timelineResponse = [responseObject mutableCopy];
[self.collectionView reloadData];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Failure: %#", error);
}];
}
- (void)nextInstagramPage:(NSIndexPath *)indexPath{
NSDictionary *page = self.timelineResponse[#"pagination"];
NSString *nextPage = page[#"next_url"];
[[InstagramClient sharedClient] getPath:[NSString stringWithFormat:#"%#",nextPage] parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
self.timelineResponse = [responseObject mutableCopy];
[self.timelineResponse addEntriesFromDictionary:responseObject];
[self.collectionView reloadData];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"Failure: %#", error);
}];
}
- (NSMutableArray *)entries {
return self.timelineResponse[#"data"];
}
- (NSArray *)pages {
return self.timelineResponse[#"pagination"];
}
- (NSURL *)imageUrlForEntryAtIndexPath:(NSIndexPath *)indexPath {
NSDictionary *entry = [self entries][indexPath.row];
NSString *imageUrlString = entry[#"images"][#"standard_resolution"][#"url"];
return [NSURL URLWithString:imageUrlString];
}
#pragma mark - UICollectionViewDelegate
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
//int y = arc4random() % 200+50;
return CGSizeMake(150, 150);
}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
RNBlurModalView *modal = [[RNBlurModalView alloc] initWithViewController:self title:#"Item Tapped!" message:#"Thank God its working"];
[modal show];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.y == roundf(scrollView.contentSize.height-scrollView.frame.size.height)) {
NSLog(#"we are at the endddd");
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[self nextInstagramPage:indexPath];
}
}
#pragma mark - UICollectionViewDataSource
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return [[self entries] count];
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
ImageCell *cell = (ImageCell *)[collectionView dequeueReusableCellWithReuseIdentifier:#"imageCell"
forIndexPath:indexPath];
NSURL *url = [self imageUrlForEntryAtIndexPath:indexPath];
NSLog(#"%#", url);
[cell.imageView setImageWithURL:url];
cell.backgroundColor = [UIColor whiteColor];
return cell;
}
-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
#pragma mark - NavigationBarButtons
- (void)didTapBarButton:(id)sender {
[self.sidePanelController showLeftPanelAnimated:YES];
}
- (void)startRefresh:(UIRefreshControl *)sender {
[self refreshInstagram];
[sender endRefreshing];
}
-(void)didTapPostButton:(id)sender {
}
#end

Answer 1

Your problem is probably arising from this line:
self.timelineResponse = [responseObject mutableCopy];
At this point, all the objects in timelineResponse are deleted. Try removing this line and I bet you'll be fine.