material-components_material-components-ios/components/Collections/examples/CollectionsGridExample.m

/*
 Copyright 2016-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 "CollectionsGridExample.h"

static const NSInteger kSectionCount = 10;
static const NSInteger kSectionItemCount = 4;
static NSString *const kReusableIdentifierItem = @"itemCellIdentifier";

@implementation CollectionsGridExample {
  NSMutableArray *_content;
  UIAlertController *_actionController;
}

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

- (void)viewDidLoad {
  [super viewDidLoad];

  // Add button to update styles.
  self.navigationItem.rightBarButtonItem =
      [[UIBarButtonItem alloc] initWithTitle:@"Update Styles"
                                       style:UIBarButtonItemStylePlain
                                      target:self
                                      action:@selector(presentActionController:)];

  // Register cell class.
  [self.collectionView registerClass:[MDCCollectionViewTextCell class]
          forCellWithReuseIdentifier:kReusableIdentifierItem];

  // Populate content.
  _content = [NSMutableArray array];
  for (NSInteger i = 0; i < kSectionCount; i++) {
    NSMutableArray *items = [NSMutableArray array];
    for (NSInteger j = 0; j < kSectionItemCount; j++) {
      NSString *itemString = [NSString stringWithFormat:@"Section-%zd Item-%zd", i, j];
      [items addObject:itemString];
    }
    [_content addObject:items];
  }

  // Customize collection view settings.
  self.styler.cellStyle = MDCCollectionViewCellStyleCard;
  self.styler.cellLayoutType = MDCCollectionViewCellLayoutTypeGrid;
  self.styler.gridPadding = 8;
  self.styler.gridColumnCount = 2;
}

#pragma mark - <UICollectionViewDataSource>

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

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

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

#pragma mark - Update Styles

- (void)toggleCellLayoutType {
  // Toggles between list and grid layout.
  BOOL isListLayout = (self.styler.cellLayoutType == MDCCollectionViewCellLayoutTypeList);
  self.styler.cellLayoutType =
      isListLayout ? MDCCollectionViewCellLayoutTypeGrid : MDCCollectionViewCellLayoutTypeList;
  [self.collectionView performBatchUpdates:nil completion:nil];
}

- (void)toggleCellStyle {
  // Toggles between card and grouped styles.
  BOOL isCardStyle = (self.styler.cellStyle == MDCCollectionViewCellStyleCard);
  self.styler.cellStyle =
      isCardStyle ? MDCCollectionViewCellStyleGrouped : MDCCollectionViewCellStyleCard;
  [self.collectionView performBatchUpdates:nil completion:nil];
}

#pragma mark - Action Controller

- (void)presentActionController:(id)sender {
  _actionController =
      [UIAlertController alertControllerWithTitle:@"Update Styles"
                                          message:nil
                                   preferredStyle:UIAlertControllerStyleActionSheet];

  [_actionController addAction:[UIAlertAction actionWithTitle:@"Toggle List/Grid Layout"
                                                        style:UIAlertActionStyleDefault
                                                      handler:^(UIAlertAction *action) {
                                                        [self toggleCellLayoutType];
                                                      }]];

  [_actionController addAction:[UIAlertAction actionWithTitle:@"Toggle Card/Grouped Style"
                                                        style:UIAlertActionStyleDefault
                                                      handler:^(UIAlertAction *action) {
                                                        [self toggleCellStyle];
                                                      }]];

  [_actionController addAction:[UIAlertAction actionWithTitle:@"Cancel"
                                                        style:UIAlertActionStyleCancel
                                                      handler:^(UIAlertAction *action) {
                                                        [self dismissActionController];
                                                      }]];

  [self presentViewController:_actionController animated:YES completion:nil];
}

- (void)dismissActionController {
  [self dismissViewControllerAnimated:YES completion:nil];
}

@end