iphone - 添加更多单元格 UICollectionView

Question

好吧，现在我通过到达屏幕底部而不是添加新单元格来替换 Instagram 中的图像。我如何添加新单元格而不是替换以前的单元格？

这是我检索下一页图像的完整实现文件:

@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;
                                        [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.collectionView cellForItemAtIndexPath:indexPath];
        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.collectionView performBatchUpdates:^{
            [self nextInstagramPage:indexPath];

        } completion:^(BOOL finished) {


        }
         ];
    }
}

#pragma mark - UICollectionViewDataSource

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {

    return [[self entries] count];

}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {

    if ( indexPath.item == ([[self entries] count] - 1) ) {
        // download more data and add it to the 'entries' array
        [self refreshInstagram];


    }

    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

这是一种添加新单元格的方法:

-(void)addNewCells {
    [self.collectionView performBatchUpdates:^{
        int resultsSize = [[self entries]count];
        [self.results addObjectsFromArray:newData];
        NSMutableArray *arrayWithIndexPaths = [NSMutableArray array];
        for (int i = resultsSize; i < resultsSize + newData.count; i++)
            [arrayWithIndexPaths addObject:[NSIndexPath indexPathForRow:i inSection:0]];
    }
     [self.collectionView insertItemsAtIndexPaths:arrayWithIndexPaths];
     }
                                  completion:nil];
}

Answer 1

您必须保留从服务返回的照片的数组。正如 Mundi 的回答所暗示的那样，字典将不起作用，因为添加字典中的响应将替换现有的键/值对。这就是为什么您会看到闪烁的原因。

将 NSMutableArray 属性添加到您的 View Controller ，并将数据中的条目添加到它。

[self.photosArray addObjectsFromArray:responseObject[@"data"]];

然后在您的 entries 方法中使用 self.photosArray。