如何使用NSFetchedResultsController和多个获取的实体设置collectionView (或TableView)

#import <CoreData/CoreData.h>

@interface ViewController () <NSFetchedResultsControllerDelegate, UICollectionViewDataSource>

@property (nonatomic, strong) NSFetchedResultsController *fetchedResultsController;
@property (nonatomic, strong) UICollectionView *collectionView;

@end

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 创建请求
    NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"YourEntity"];
    
    // 设置排序规则
    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"yourProperty" ascending:YES];
    fetchRequest.sortDescriptors = @[sortDescriptor];
    
    // 设置谓词
    // fetchRequest.predicate = [NSPredicate predicateWithFormat:@"yourPredicate"];
    
    // 初始化NSFetchedResultsController
    self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.yourManagedObjectContext sectionNameKeyPath:nil cacheName:nil];
    self.fetchedResultsController.delegate = self;
    
    // 执行查询
    NSError *error = nil;
    [self.fetchedResultsController performFetch:&error];
    if (error) {
        NSLog(@"Error performing fetch: %@", error);
    }
    
    // 初始化并配置UICollectionView
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
    self.collectionView.dataSource = self;
    [self.collectionView registerClass:[YourCollectionViewCell class] forCellWithReuseIdentifier:@"YourCell"];
    [self.view addSubview:self.collectionView];
}

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
    [self.collectionView beginUpdates];
}

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
    switch (type) {
        case NSFetchedResultsChangeInsert:
            [self.collectionView insertItemsAtIndexPaths:@[newIndexPath]];
            break;
        case NSFetchedResultsChangeDelete:
            [self.collectionView deleteItemsAtIndexPaths:@[indexPath]];
            break;
        case NSFetchedResultsChangeUpdate:
            [self.collectionView reloadItemsAtIndexPaths:@[indexPath]];
            break;
        case NSFetchedResultsChangeMove:
            [self.collectionView moveItemAtIndexPath:indexPath toIndexPath:newIndexPath];
            break;
        default:
            break;
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    [self.collectionView endUpdates];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return self.fetchedResultsController.sections.count;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    id<NSFetchedResultsSectionInfo> sectionInfo = self.fetchedResultsController.sections[section];
    return sectionInfo.numberOfObjects;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    YourCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"YourCell" forIndexPath:indexPath];
    NSManagedObject *object = [self.fetchedResultsController objectAtIndexPath:indexPath];
    
    // 根据实体的属性配置cell的显示内容
    // cell.textLabel.text = [object valueForKey:@"yourProperty"];
    
    return cell;
}