UICollectionView with section headers like a UITab

问题:

I have a quick question has anyone been able to successfully create and implement section headers in a CollectionView similar to the headers in a TableView ? I did a lot of research and found snippets of code but no real example from anyone who successfully achieved this. I have a CollectionView of photos, What I am trying to achieve is to group them up in sections depending on the month which they were taken. I have managed to split them up into those sections but all I have now is a blank header right above the start of each section. What I want to do is display the months in those currently blank headers. The same way the letters for each section are displayed in the Tableview that displays the contacts. Thanks for your responses in advance.

回答1:

1. Enable the section header/footer view in Storyboard.

2. Implement collectionView:viewForSupplementaryElementOfKind method.

see This Link

回答2:

Adding section headers in a collection view works for me with the following set up:

1. add a xib file to define the header view content. The xib file contains only one cell type definition. In my case, the header view has a custom type (ImageCollectionViewHeaderCell) which derives from UICollectionViewCell. I think it is required but I'm not sure. The cell identifier is also set to predefined string (e.g.) "ImageCollectionViewHeaderCellId"

2. add header and implementation files for the custom type. It is convenient to have a method to get its UINib object (a kind of proxy for the xib file created at step 1)

   @implementation ImageCollectionViewHeaderCell
   + (UINib*) nib
   {
     return [UINib nibWithNibName:@"nameOfXibFileCreatedAtStep1" bundle:nil];
   }
   
   @end
   

3. in the collection view controller (which, in my case, is also the dataSource and delegate of the UICollectionView), in the viewDidLoad method, add the registration for the supplementary element type

   - (void) viewDidLoad
   {
      [_collectionView registerNib:[ImageCollectionViewHeaderCell nib] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"ImageCollectionViewHeaderCellId"];
   }
   

4. in the collection view controller, add the methods to return a non null header height and the header view instances

   - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
   {
     return CGSizeMake(0., 30.);
   }
   
   - (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
   {
     NSAssert([kind isEqualToString:UICollectionElementKindSectionHeader], @"Unexpected supplementary element kind");
     UICollectionReusableView* cell = [collectionView dequeueReusableSupplementaryViewOfKind:kind
                                                                 withReuseIdentifier:ImageCollectionViewHeaderCellIdentifier
                                                                        forIndexPath:indexPath];
   
     NSAssert([cell isKindOfClass:[ImageCollectionViewHeaderCell class]], @"Unexpected class for header cell");
   
     ImageCollectionViewHeaderCell* header_view = (ImageCollectionViewHeaderCell*) cell;
   
     // custom content
   
     return cell;
   }