Question

I want to populate an array after I selected a row. Now I want to populate an array using a function. This is what the situation is. I have a tableview which displays albums titles. When you select a row you show all pictures using the FGallery library. Here is my function for populating my array.

- (NSMutableArray *)getAllPicturesOfAlbumId: (int)AlbumId
{
    NSLog(@"tot hier");
    _picturesForAlbum = [[NSMutableArray alloc]init];
    NSArray *results = [[NSArray alloc]init];
    //picture_Url = @"";
    NSLog(@"tot hier");
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"whichAlbum.album_id == %d", AlbumId];
    [request setEntity:[NSEntityDescription entityForName:@"Picture" inManagedObjectContext:self.genkDatabase.managedObjectContext]];
    [request setPredicate:predicate];
    NSError *error = nil;
    NSLog(@"tot hier");
    results = [self.genkDatabase.managedObjectContext executeFetchRequest:request error:&error];
    if (results == nil) {
        // handle errors
        NSLog(@"geen resultaten");
    } else if (results.count == 0) {
        // nothing found
        NSLog(@"0 resultaten");
    } else {
        for(int i = 0; i < results.count ; i++){
           // NSLog(@"%@",[results valueForKey:@"url"]);
            [_picturesForAlbum addObject: [results valueForKey:@"url"]];
        }
    }

    return _picturesForAlbum;
}

Here are my FGallery methods.

- (int)numberOfPhotosForPhotoGallery:(FGalleryViewController *)gallery
{
     return [networkImages count];

}


- (FGalleryPhotoSourceType)photoGallery:(FGalleryViewController *)gallery sourceTypeForPhotoAtIndex:(NSUInteger)index
{
     return FGalleryPhotoSourceTypeNetwork;
}


- (NSString*)photoGallery:(FGalleryViewController *)gallery urlForPhotoSize:(FGalleryPhotoSize)size atIndex:(NSUInteger)index {
    return [networkImages objectAtIndex:index];
}

And this is what I do in my didSelectRowAtIndexPath

networkImages = [[NSArray alloc] initWithArray:[self getAllPicturesOfAlbumId:indexPath.row]];
networkGallery = [[FGalleryViewController alloc] initWithPhotoSource:self];
[self.navigationController pushViewController:networkGallery animated:YES];

Put for some reason or another my networkImages is populated several times with the array it gets back from the method “getAllPicturesOfAlbumId”
Because of that I think I get the following error.

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayI length]: unrecognized selector sent to instance 0xa15d090'

Anybody has an idea what the problem is?

Thanks in advance.

Answer 1

Calling valueForKey on an array returns an array of all the value for that key. So, in the method getAllPicturesOfAlbumId, you shouldn’t loop through results, just return [results valueForKey:@”URL”] (so no need to even create the _picturesForAlbum array).