滚动时出现在 collectionview 中的标题 up/down

Question

当应用运行时，标题（collectionview 中的标签）没有出现。向上或向下滚动然后出现标题。同样在 numberOfItemsInSection 中，[新闻计数] 结果为 0。

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- (void)viewDidLoad
{
    NSLog(@"viewDidLoad ");
    [super viewDidLoad];
    leftMenu.target=self.revealViewController;
    leftMenu.action=@selector(revealToggle:);
    self.title=@"Main";
    [self.view addGestureRecognizer:self.revealViewController.panGestureRecognizer];


    [UIApplication sharedApplication].networkActivityIndicatorVisible=YES;
    NSURL *url=[NSURL URLWithString:@"http://www.test.com/ios/GetMainInfoByCat.php?cat_id=76"];
    NSURLRequest *request=[NSURLRequest requestWithURL:url];
    [[NSURLConnection alloc] initWithRequest:request delegate:self];

    //self.collectionview.dataSource=self;
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    data=[[NSMutableData alloc]init];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)Thedata
{
    [data appendData:Thedata];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"connectionDidFinishLoading ");
    [UIApplication sharedApplication].networkActivityIndicatorVisible=NO;

    dnews=[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
    news=[dnews objectForKey:@"news_main_info_by_cat"];
    NSString *str=[news valueForKey:@"img_url"];

    //[self.collectionview reloadData];
    //NSLog(@"%@",str);
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    UIAlertView *erroMsg=[[UIAlertView alloc]initWithTitle:@"Error" message:@"Qoşula bilmədi. İnternet bağlantınızı yoxlayın" delegate:nil cancelButtonTitle:@"Dismiss" otherButtonTitles:nil, nil];
    [erroMsg show];
    [UIApplication sharedApplication].networkActivityIndicatorVisible=NO;
}

-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    [collectionView.collectionViewLayout invalidateLayout];
    return 1;
}

-(NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    NSLog(@"%i",[news count]);
    [collectionView.collectionViewLayout invalidateLayout];
    return 10;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CollectionViewCell *cell=(UICollectionView *)[collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
    cell.newsTitle.text=[[news objectAtIndex:indexPath.row] objectForKey:@"post_title"];
    //cell.newsImage.image=[NSData dataWithContentsOfURL:[NSURL URLWithString:[[news objectAtIndex:indexPath.row] objectForKey:@"img_url"]]];
    //[[news objectAtIndex:indexPath.row] objectForKey:@"img_url"];
    return cell;
}

Answer 1

--> 当您滚动 collectionview 或 tableview 时，它们会重新加载数据，因此当您获得数组后，请重新加载滚动视图，这一定会对您有所帮助。

Answer 2

调用重新加载数据

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSLog(@"connectionDidFinishLoading ");
    [UIApplication sharedApplication].networkActivityIndicatorVisible=NO;

    dnews=[NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
    news=[dnews objectForKey:@"news_main_info_by_cat"];
    NSString *str=[news valueForKey:@"img_url"];

    [self.collectionview reloadData];
}

更新：确保IBoutlet连接到collectionView

滚动时出现在 collectionview 中的标题 up/down

titles appearing in collectionview when scroll up/down

json

ios

uicollectionview

uicollectionviewcell