components/Collections/examples/supplemental/CollectionsEditingManyCellsExampleSupplemental.m

/*
 Copyright 2017-present the Material Components for iOS authors. All Rights Reserved.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import "CollectionsEditingManyCellsExampleSupplemental.h"

@implementation CollectionsEditingManyCellsExample (Supplemental)

#pragma mark - CatalogByConvention

+ (NSArray *)catalogBreadcrumbs {
  return @[ @"Collections", @"Cell Editing Example (1000+)" ];
}

+ (BOOL)catalogIsPrimaryDemo {
  return NO;
}

+ (BOOL)catalogIsPresentable {
  return NO;
}

#pragma mark - <UICollectionViewDataSource>

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
  return [self.content count];
}

- (NSInteger)collectionView:(UICollectionView *)collectionView
     numberOfItemsInSection:(NSInteger)section {
  return [self.content[section] count];
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                  cellForItemAtIndexPath:(NSIndexPath *)indexPath {
  MDCCollectionViewTextCell *cell =
  [collectionView dequeueReusableCellWithReuseIdentifier:kCollectionsEditingManyCellsCellIdentifierItem
                                            forIndexPath:indexPath];
  cell.textLabel.text = self.content[indexPath.section][indexPath.item];
  return cell;
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView
           viewForSupplementaryElementOfKind:(NSString *)kind
                                 atIndexPath:(NSIndexPath *)indexPath {
  // If you have defined your own supplementary views, deque them here
  if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
    MDCCollectionViewTextCell *sectionHeader =
    [collectionView dequeueReusableSupplementaryViewOfKind:kind
                                       withReuseIdentifier:kCollectionsEditingManyCellsHeaderReuseIdentifier
                                              forIndexPath:indexPath];

    NSAssert(sectionHeader != nil, @"Unable to dequeue SupplementaryView");

    if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
      sectionHeader.textLabel.text =
      [NSString stringWithFormat:@"Section %lu Header", (long)indexPath.section];
    }

    return sectionHeader;
  }

  // Otherwise, pass the kind to super to let MDCCollectionViewController handle the request
  return [super collectionView:collectionView
viewForSupplementaryElementOfKind:kind
                   atIndexPath:indexPath];
}

#pragma mark - <MDCCollectionViewEditingDelegate>

- (BOOL)collectionViewAllowsEditing:(UICollectionView *)collectionView {
  return YES;
}

- (BOOL)collectionViewAllowsReordering:(UICollectionView *)collectionView {
  return YES;
}

- (BOOL)collectionViewAllowsSwipeToDismissItem:(UICollectionView *)collectionView {
  return self.editor.isEditing;
}

- (void)collectionView:(UICollectionView *)collectionView
willDeleteItemsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths {
  // First sort reverse order then remove. This is done because when we delete an index path the
  // higher rows shift down, altering the index paths of those that we would like to delete in the
  // next iteration of this loop.
  NSArray *sortedArray = [indexPaths sortedArrayUsingSelector:@selector(compare:)];
  for (NSIndexPath *indexPath in [sortedArray reverseObjectEnumerator]) {
    [self.content[indexPath.section] removeObjectAtIndex:indexPath.item];
  }
}

- (void)collectionView:(UICollectionView *)collectionView
willMoveItemAtIndexPath:(NSIndexPath *)indexPath
           toIndexPath:(NSIndexPath *)newIndexPath {
  if (indexPath.section == newIndexPath.section) {
    // Exchange data within same section.
    [self.content[indexPath.section] exchangeObjectAtIndex:indexPath.item
                                         withObjectAtIndex:newIndexPath.item];
  } else {
    // Since moving to different section, first remove data from index path and insert
    // at new index path.
    id movedObject = [self.content[indexPath.section] objectAtIndex:indexPath.item];
    [self.content[indexPath.section] removeObjectAtIndex:indexPath.item];
    [self.content[newIndexPath.section] insertObject:movedObject atIndex:newIndexPath.item];
  }
}

#pragma mark UICollectionViewFlowLayoutDelegate

- (CGSize)collectionView:(UICollectionView *)collectionView
                  layout:(UICollectionViewLayout *)collectionViewLayout
referenceSizeForHeaderInSection:(NSInteger)section {
  return CGSizeMake(collectionView.bounds.size.width, MDCCellDefaultOneLineHeight);
}

@end