IOS基础-UICollectionView

- (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
  
 
// 可以给layout设置全局属性
  UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
  // default is UICollectionViewScrollDirectionVetical
  //layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
  
  _collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
  [self.view addSubview:_collectionView];
  _collectionView.backgroundColor = [UIColor lightGrayColor];
  _collectionView.delegate = self;
  _collectionView.dataSource = self;
  // 注册类，是用纯代码生成的collectiviewcell类才行
  //[_collectionView registerClass:[CollectionViewCell class] forCellWithReuseIdentifier:@"CellIdentifier"];
  [_collectionView registerNib:[UINib nibWithNibName:@"CollectionViewCell" bundle:nil] forCellWithReuseIdentifier:@"CellIdentifier"];
}

#pragma mark - UICollectionViewDataSource
// 指定Section个数
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
  return 3;
}


// 指定section中的collectionViewCell的个数
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
  return 10;
}

// 配置section中的collectionViewCell的显示
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
  CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CellIdentifier" forIndexPath:indexPath];
  cell.backgroundColor = [UIColor redColor];
  cell.textLabel.text = [NSString stringWithFormat:@"(%ld %ld)", indexPath.section, indexPath.row];
  
  return cell;
}

#pragma mark - UICollectionViewDelegateFlowLayout
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
  return CGSizeMake(self.view.frame.size.width / 3 - 10, self.view.frame.size.width / 3 - 10);
}

// 设置每个cell上下左右相距
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
  return UIEdgeInsetsMake(5, 5, 5, 5);
}

// 设置最小行间距，也就是前一行与后一行的中间最小间隔
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {
  return 10;
}

// 设置最小列间距，也就是左行与右一行的中间最小间隔
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {
  return 10;
}

// 设置section头视图的参考大小，与tableheaderview类似
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section {
  return CGSizeMake(self.view.frame.size.width, 40);
}

// 设置section尾视图的参考大小，与tablefooterview类似
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section {
  return CGSizeMake(self.view.frame.size.width, 40);
}

#pragma mark - UICollectionViewDelegate
// 允许选中时，高亮
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath {
  NSLog(@"%s", __FUNCTION__);
  return YES;
}

// 高亮完成后回调
- (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath {
  NSLog(@"%s", __FUNCTION__);
}

// 由高亮转成非高亮完成时的回调
- (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIndexPath:(NSIndexPath *)indexPath {
  NSLog(@"%s", __FUNCTION__);
}

// 设置是否允许选中
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath {
  NSLog(@"%s", __FUNCTION__);
  return YES;
}

// 设置是否允许取消选中
- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
  NSLog(@"%s", __FUNCTION__);
  return YES;
}

// 选中操作
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
  NSLog(@"%s", __FUNCTION__);
}

// 取消选中操作
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
  NSLog(@"%s", __FUNCTION__);
}