PMBrowsingCollectionView

PMBrowsingCollectionView is a subclass of UICollectionView that implements a new interaction for easily browsing through a collection of cells by introducing the concept of expanded vs. collapsed sections.

Requirements & Notes

PMBrowsingCollectionView was built for iOS and requires a minimum iOS target of iOS 7.
Thorough commenting of header files is currently in progress. (6/12/14).
PMBrowsingCollectionView will not support resizing until dynamic cell resizing is added in iOS8

How To Get Started

Check out the documentation (coming soon).

Installation with CocoaPods

PMBrowsingCollectionView is available through CocoaPods. CocoaPods is a dependency manager for Objective-C, which automates and simplifies the process of using 3rd-party libraries like PMBrowsingCollectionView in your projects. See the "Getting Started" guide for more information.

Podfile

To install, simply add the following line to your Podfile.

platform :ios, '7.0'
pod "PMBrowsingCollectionView"

Usage

To see PMBrowsingCollectionView in action, run the example project at /Example/PMBrowsingCollectionView-iOSExample.xcworkspace. After installing the PMBrowsingCollectionView pod, integrating into your project is as easy as creating a typical UICollectionView:

UICollectionViewFlowLayout *layout = [UICollectionViewFlowLayout new];
layout.scrollDirection = UICollectionViewScrollDirectionVertical;
layout.minimumInteritemSpacing = 2.0f;
layout.minimumLineSpacing = 2.0f;
	
PMBrowsingCollectionView *collectionView = [PMBrowsingCollectionView collectionViewWithFrame:self.view.bounds
                                                                            collectionViewLayout:layout];
collectionView.delegate = self;
collectionView.dataSource = self;
[collectionView registerClass:[UICollectionViewCell class]
            forCellWithReuseIdentifier:@"cellReuseIdentifier"];
[collectionView registerClass:[UICollectionReusableView class]
            forSupplementaryViewOfKind:UICollectionElementKindSectionHeader
                   withReuseIdentifier:@"headerReuseIdentifier"];
[self.view addSubview:collectionView];

- (UICollectionViewCell *)collectionView:(PMBrowsingCollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
	UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellReuseIdentifier" forIndexPath:indexPath];
	NSUInteger normalizedIndex = [collectionView normalizeItemIndex:indexPath.item forSection:indexPath.section];
	/*
	* Configure cell based on indexPath.section and normalizedIndex
	*/
	return cell;
}

PMBrowsingCollectionViewDelegate adds three optional methods to the UICollectionViewDelegateFlowLayout:

- (CGFloat) collectionView:(PMBrowsingCollectionView *)collectionView shadowRadiusForSection:(NSInteger)section
{
    return 20.0f;
}

- (UIColor *) collectionView:(PMBrowsingCollectionView *)collectionView shadowColorForSection:(NSInteger)section
{
    return [UIColor blackColor];
}

// Only called when section is in a collapsed state.
- (void) collectionView:(PMBrowsingCollectionView *)collectionView willCenterItemAtIndexPath:(NSIndexPath *)indexPath
{
	NSUInteger normalizedIndex = [collectionView normalizeIndex:indexPath.item];
	DLog(@"Will center cell at section index %d, item index %d", indexPath.section, normalizedIndex);
}

Discussion

To achieve infinite scrolling, PMCircularCollectionView employes a technique described in this blog post which multiplies the content size and consequently the number of index paths. Thus, it is possible for dataSource and delegate methods to pass an index path with item == 15, when less than 16 items were returned to the -collectionView:numberOfItemsInSection: delegate method. As seen in the examples above, call -normalizeItemIndex:forSection to change the item index to the correct value.

Communication

If you need help, use Stack Overflow. (Tag 'PMTabBarController')
If you'd like to ask a general question, use Stack Overflow.
If you found a bug, open an issue.
If you have a feature request, open an issue.
If you want to contribute, submit a pull request.

Author

Peter Meyers

License

PMBrowsingCollectionView is available under the MIT license. See the LICENSE file for more info.

lisafiedler / PMBrowsingCollectionView