iphone - 如何删除所有项目并向 UICollectionView 添加新项目？

Question

在某些事件上，

我想删除 uicollectionview 中的所有单元格，并添加新单元格。(将作为网络调用的结果填充)

我尝试使用 deleteItemsAtIndexPaths。reloadSections、deleteSections/insertSections。

他们每个人都让我的应用程序崩溃了。

下面是我的代码。

NSMutableArray* indexPathArray = [[NSMutableArray alloc] init];

for(int i=0; i < [self.jsonAlbumImageArray count]; ++i)
{
    NSIndexPath* newPath = [NSIndexPath indexPathForRow:i inSection:0];
    [indexPathArray addObject: newPath];
}

[self.jsonAlbumImageArray removeAllObjects];

if(indexPathArray.count > 0 )
{
    [self.collectionView performBatchUpdates:^{
            [self.collectionView deleteItemsAtIndexPaths:indexPathArray];
        }
    completion: nil];
}

// NSIndexSet *indexSet = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, 1)];                                                                                                                                                                                        
// NSIndexSet* indexSet = [NSIndexSet indexSetWithIndex:0];                                                                                                                                                                                                                 
// [self.collectionView reloadSections:indexSet];                                                                                                                                                                                                                           

[self get_IMAGE_LIST_FROM_SERVER];

Answer 1

如果您需要比 [collectionView reloadData] 提供的动画更流畅的动画，您可以使用插入和删除方法来实现，这里有一个示例。

-(void)deleteItemsFromDataSourceAtIndexPaths:(NSArray  *)itemPaths
{
    NSMutableIndexSet *indexSet = [NSMutableIndexSet indexSet];
    for (NSIndexPath *itemPath  in itemPaths) {
        [indexSet addIndex:itemPath.row];
    }
    [self.apps removeObjectsAtIndexes:indexSet];
}

-(void)insertItems:(NSArray*)items ToDataSourceAtIndexPaths:(NSArray  *)itemPaths
{
    NSMutableIndexSet *indexSet = [NSMutableIndexSet indexSet];
    for (NSIndexPath *itemPath  in itemPaths) {
        [indexSet addIndex:itemPath.row];
    }
    [self.apps insertObjects:items atIndexes:indexSet];
}

-(void)reloadDataSmooth{
        [self.collectionView performBatchUpdates:^{

            NSMutableArray *arrayWithIndexPathsDelete = [NSMutableArray array];
            NSMutableArray *arrayWithIndexPathsInsert = [NSMutableArray array];

            int itemCount = [self.items count];

            for (int d = 0; d<itemCount; d++) {
                [arrayWithIndexPathsDelete addObject:[NSIndexPath indexPathForRow:d inSection:0]];
            }
            [self deleteItemsFromDataSourceAtIndexPaths:arrayWithIndexPathsDelete];
            [self.collectionView deleteItemsAtIndexPaths:arrayWithIndexPathsDelete];

            int newItemCount = [newItems count];

            for (int i=0; i<newAppCount; i++) {
                [arrayWithIndexPathsInsert addObject:[NSIndexPath indexPathForRow:i inSection:0]];
            }
            [self insertItems:newItems ToDataSourceAtIndexPaths:arrayWithIndexPathsInsert];

            [self.collectionView insertItemsAtIndexPaths:arrayWithIndexPathsInsert];
        }
        completion:nil];
    }
}