NSFetchedResultsControllerDelegate 包装用于 UICollectionView 动画变化

用法

只是

pod 'ABCollectionViewFRC'

并替换此代码（以 MagicalRecord 为例）

- (NSFetchedResultsController *)frc
{
    if (_frc == nil) {
        _frc = [MenuItem MR_fetchAllSortedBy:@"item_id" ascending:YES withPredicate:
                [NSPredicate predicateWithFormat:@"section = %@",self.menuSection] groupBy:nil delegate:self];
    }
    return _frc;
}

用此代码替换

@property (nonatomic, strong) id<NSFetchedResultsControllerDelegate> delegateWrapper;

...

- (id<NSFetchedResultsControllerDelegate>)delegateWrapper
{
    if (_delegateWrapper == nil)
        _delegateWrapper = [[ABCollectionViewFRC alloc] initWithCollectionView:self.collectionView delegate:self];
    return _delegateWrapper;
}

- (NSFetchedResultsController *)frc
{
    if (_frc == nil) {
        _frc = [MenuItem MR_fetchAllSortedBy:@"item_id" ascending:YES withPredicate:
                [NSPredicate predicateWithFormat:@"section = %@",self.menuSection] groupBy:nil delegate:self.delegateWrapper];
    }
    return _frc;
}

您只需将代理设置为 ABCollectionViewFRC 而不是仅为 self，然后您将能够动画化 UICollectionView 变化

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

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id<NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
    switch (type) {
        case NSFetchedResultsChangeInsert:
            [self.collectionView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]];
            break;
        case NSFetchedResultsChangeDelete:
            [self.collectionView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]];
            break;
        default:
            break;
    }
}

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