components/Chips/examples/ChipsActionExampleViewController.m

/*
 Copyright 2018-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 "ChipsExamplesSupplemental.h"

#import "MaterialChips.h"
#import "MaterialChips+ChipThemer.h"

@implementation ChipsActionExampleViewController {
  UICollectionView *_collectionView;
  MDCChipView *_sizingChip;
  BOOL _isOutlined;
}

- (id)init {
  self = [super init];
  if (self) {
    self.colorScheme = [[MDCSemanticColorScheme alloc] init];
  }
  return self;
}

- (void)loadView {
  [super loadView];

  // Our preferred CollectionView Layout For chips
  MDCChipCollectionViewFlowLayout *layout = [[MDCChipCollectionViewFlowLayout alloc] init];
  layout.minimumInteritemSpacing = 10;


  // Action chips should allow single selection, collection view default is based on single
  // selection. Note that MDCChipCollectionViewCell manages the state of the chip accordingly.
  _collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];

  // Since there is no scrolling turning off the delaysContentTouches makes the cells respond faster
  _collectionView.delaysContentTouches = NO;

  // Collection view setup
  _collectionView.dataSource = self;
  _collectionView.delegate = self;
  _collectionView.backgroundColor = [UIColor whiteColor];
  _collectionView.contentInset = UIEdgeInsetsMake(4, 8, 4, 8);
  [_collectionView registerClass:[MDCChipCollectionViewCell class]
      forCellWithReuseIdentifier:@"Cell"];

  // This is used to calculate the size of each chip based on the chip setup
  _sizingChip = [[MDCChipView alloc] init];

  [self.view addSubview:_collectionView];
}

- (void)viewDidLoad {
  [super viewDidLoad];

  _isOutlined = NO;
  self.navigationItem.rightBarButtonItem =
      [[UIBarButtonItem alloc] initWithTitle:@"Outlined Style"
                                       style:UIBarButtonItemStylePlain
                                      target:self
                                      action:@selector(switchStyle)];
}

- (void)switchStyle {
  _isOutlined = !_isOutlined;
  NSString *buttonTitle = _isOutlined ? @"Filled Style" : @"Outlined Style";
  [self.navigationItem.rightBarButtonItem setTitle:buttonTitle];
  NSArray *indexPaths = [_collectionView indexPathsForSelectedItems];
  [_collectionView reloadData];
  for (NSIndexPath *path in indexPaths) {
    [_collectionView selectItemAtIndexPath:path
                                  animated:NO
                            scrollPosition:UICollectionViewScrollPositionNone];
  }
}


- (void)viewWillLayoutSubviews {
  [super viewWillLayoutSubviews];

  _collectionView.frame = self.view.bounds;
}

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

- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                           cellForItemAtIndexPath:(NSIndexPath *)indexPath {
  MDCChipCollectionViewCell *cell =
      [collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];
  MDCChipView *chipView = cell.chipView;

  // Customize Chip
  chipView.titleLabel.text = self.titles[indexPath.row];

  MDCChipViewScheme *scheme = [[MDCChipViewScheme alloc] init];
  scheme.colorScheme = self.colorScheme;
  
  // Apply Theming
  if (_isOutlined) {
    [MDCChipViewThemer applyOutlinedVariantWithScheme:scheme toChipView:chipView];
  } else {
    [MDCChipViewThemer applyScheme:scheme toChipView:chipView];
  }

  return cell;
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
  // For action chips, we never want the chip to stay in selected state.
  // Other possible apporaches would be relying on theming or Customizing collectionViewCell
  // selected state.
  [collectionView deselectItemAtIndexPath:indexPath animated:NO];

  // Do the action related to the chip
  [self setTitle:[NSString stringWithFormat:@"Action %d", (int)indexPath.row]];

}

- (CGSize)collectionView:(UICollectionView *)collectionView
                  layout:(UICollectionViewLayout*)collectionViewLayout
  sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
  _sizingChip.titleLabel.text = self.titles[indexPath.row];
  return [_sizingChip sizeThatFits:collectionView.bounds.size];
}

- (NSArray *)titles {
  if (!_titles) {
    _titles = @[
                @"Change Title to Action 0",
                @"Change Title to Action 1",
                @"Change Title to Action 2",
                @"Change Title to Action 3",
                ];
  }
  return _titles;
}

@end