Fehler beim Laden des Bildes in einer UICollectionView

Question

Ich brauche flickr öffentliche Bilder in einer UICollectionView anzuzeigen. Ich habe alle Sachen gemacht, aber Bilder laden nicht in UICollectionView. Ich bin neu im Ziel-c. Bitte helfen Sie.

authorIds = [[NSMutableArray alloc] init]; 
    dateTaken = [[NSMutableArray alloc] init]; 
    smallImageUrlArray = [[NSMutableArray alloc] init]; 
    largeImageUrlArray = [[NSMutableArray alloc] init]; 
    smallImageArray = [[NSMutableArray alloc] init]; 

    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init]; 
    layout.minimumLineSpacing = 10; 
    layout.minimumInteritemSpacing = 10; 
    layout.sectionInset = UIEdgeInsetsMake(110, 20, 20, 20); 
    _collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:layout]; 
    [_collectionView setDataSource:self]; 
    [_collectionView setDelegate:self]; 
    [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cellIdentifier"]; 
    [_collectionView setBackgroundColor:[UIColor blackColor]]; 
    [self.view addSubview:_collectionView]; 



    - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section 
    { 
     return totalImageNo; 
    } 


    - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath 
    { 
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath]; 

    UIImageView *cellImageView = (UIImageView *)[cell viewWithTag:100]; 

    cellImageView.image = [UIImage imageNamed:[smallImageUrlArray objectAtIndex:indexPath.row]]; 
    //[self.view addSubview:cellImageView]; 
    [cell.backgroundView addSubview:cellImageView]; 





    // NSLog(@"%@",[smallImageUrlArray objectAtIndex:indexPath.row]); //Here can show Img's values correctly 

    cell.backgroundColor=[UIColor darkGrayColor]; 
    return cell; 
} 

    - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath 
    { 
     return CGSizeMake(160, 160); 
    } 

In unten werde ich Flickr Bilder abrufen und in Array speichern. möchte dann das smallImageArray in der UICollection-Ansicht laden. aber nichts zeigt sich.

-(void)fetchFlickrPublicImages 
    { 
     NSString *urlString = [NSString stringWithFormat:@"http://api.flickr.com/services/feeds/photos_public.gne?format=json&tags=data"]; 

     NSURL *url = [NSURL URLWithString:urlString]; 

     NSData *badJSON = [NSData dataWithContentsOfURL:url]; 

     NSString *dataAsString = [NSString stringWithUTF8String:[badJSON bytes]]; 

     NSString *correctedJSONString = [NSString stringWithString:[dataAsString substringWithRange:NSMakeRange (15, dataAsString.length-15-1)]]; 
     correctedJSONString = [correctedJSONString stringByReplacingOccurrencesOfString:@"\\'" withString:@"'"]; 

     NSData *correctedData = [correctedJSONString dataUsingEncoding:NSUTF8StringEncoding]; 

     NSError* error; 
     NSDictionary *json = [NSJSONSerialization JSONObjectWithData:correctedData options:kNilOptions error:&error]; 

     NSArray *images = [json objectForKey:@"items"]; 

     for (NSDictionary *image in images) 
     { 
      NSString *authorId = [image objectForKey:@"author_id"]; 

      [authorIds addObject:(authorId.length > 0 ? authorId: @"Untitled")]; 

      NSString *largeImageUrl = [NSString stringWithFormat:@"%@",[[image objectForKey:@"media"] objectForKey:@"m"]]; 

      NSString *smallImageUrl = [largeImageUrl stringByReplacingOccurrencesOfString:@"_m" withString:@"_s"]; 

      [smallImageUrlArray addObject:smallImageUrl]; 

      [dateTaken addObject:[NSString stringWithFormat:@"%@",[image objectForKey:@"date_taken"]]]; 

      [largeImageUrlArray addObject:[NSString stringWithFormat:@"%@",[[image objectForKey:@"media"] objectForKey:@"m"]]]; 

      totalImageNo = authorIds.count; 
     } 


     for (int i=0; i< smallImageUrlArray.count; i++) { 

      UIImage * image = [UIImage imageWithData:[NSData dataWithContentsOfURL: 
                 [NSURL URLWithString:[smallImageUrlArray objectAtIndex:i]]]]; 

      [smallImageArray addObject:image]; 
     } 
     NSLog(@"%@", smallImageArray); 

     NSLog(@"%ld", (long)totalImageNo); 
     // NSLog(@"authorIds: %@\n\n", authorIds); 
     // NSLog(@"photoURLsLareImage: %@\n\n", smallImageUrlArray); 
     // NSLog(@"photoURLsLareImage: %@\n\n", largeImageUrlArray); 

    } 

Answer 1

Sie sollten Ihre UIImageView die Sammlung Ansicht Zelle contentView, NICHT backgroundView hinzufügen.

Answer 2

in Ihrem Code

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath 
    { 
UIImageView *cellImageView = (UIImageView *)[cell viewWithTag:100]; 
cellImageView.image = [UIImage imageNamed:[smallImageUrlArray objectAtIndex:indexPath.row]]; 
[cell.backgroundView addSubview:cellImageView]; 
} 

Sie Bild als URL zuweisen. aber in Ihrer Methode namens fetchFlickrPublicImages, wo Sie Bilder direkt herunterladen.

besser schreiben Sie Code wie

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath 
    { 
UIImageView *cellImageView = (UIImageView *)[cell viewWithTag:100]; 
cellImageView.image =(UIImage*)[smallImageArray objectAtIndex:indexPath.row]; 
[cell.contentView addSubView cellImageView]; 
}