BRScroller

Memory-friendly iOS horizontally scrolling view.

BRScroller provides a UIScrollView subclass that efficiently manages horizontally-scrolling pages of content, much like a UITableView manages vertically-scrolling rows of content. In addition, BRScroller provides some scaffolding for the memory-efficient and UI-responsive display of high resolution content, such as photos. In this respect, BRScroller can be used in similar ways as MWPhotoBrowser, TTPhotoViewController, or EGOPhotoViewer. Where BRScroller differs, however, is that it does not provide any built-in UI. Instead of forcing any particular UI, you can build any UI that suits your application, relying on BRScroller to perform just the low-level (dare I say, boring) work of helping you managing memory efficiently.

Requirements

BRScroller has no dependencies outside the iOS SDK. It supports deployment to any iOS device, version 5.1 or later.

Example Usage

See the BRScrollerDemo project, included in this project, that demonstrates different ways of using BRScroller. Here is a description of the demos available in that project:

• SimpleViewController

  A very simple demonstration of BRScrollerView that shows how the basic principles of managed page views are handled. If you've every coded a UITableViewController you should feel right at home.

• AsyncPhotoViewController

  A demo that showcases a common scenario: the display of images in a similar way to the iOS built-in Photos app. Smaller preview images are shown while scrolling between photos. When you pinch to zoom any particular photo, the full-resolution version of that is shown.

• PdfViewController

  A demo that showcases the BRCachedPreviewPdfPageZoomView to present pages from a PDF file. The BRScrollerView is used to swipe between all pages of the PDF, with each page presented in its own zoom-able scroll view. Smaller preview images are shown quickly while the PDF content is drawn using a CATiledLayer, which makes the PDF content remain sharp while zooming.

• DemoTiledViewController

  Demonstrates using a CATiledLayer backed view to render arbitrarily large content.

• MultiViewController

  Shows how multiple scrollers can be used together, with a full-screen scroller representing full-detail pages of content and a small ribbon scroller representing thumbnails corresponding to the full-detail pages. Tapping on a thumbnail causes the full-detail page to animate into view.

• InfiniteViewController

  BRScroller sports an infinite mode, in which the number of pages are not necessarily known in advance (or there are just a lot of pages!). This mode works by defining an origin page, and all other pages are relative to that origin (e.g. -1 for immediately left or 1 for immediately right).

• ReverseViewController

  BRScroller sports a reverse layout mode, in which the pages are positioned in right-to-left order, rather than the default left-to-right order.

Project Integration

You can integrate BRScroller via CocoaPods, or manually as either a dependent project or static framework.

via CocoaPods

Install CocoaPods if not already available:

$ [sudo] gem install cocoapods
$ pod setup

Change to the directory of your Xcode project, and create a file named Podfile with contents similar to this:

platform :ios, '5.1' 
pod 'BRScroller', '~> 1.0'

Install into your project:

$ pod install

Open your project in Xcode using the .xcworkspace file CocoaPods generated. There are two pod submodules available:

1. BRScroller/View-Support - for some UIView support for scroller page views.
2. BRScroller/Image-Support - for some UIView support for asynchronous UIImage loading.

via static framework

You can integrate BRScroller into your project in a couple of ways. First, the BRScroller Xcode project includes a target called BRScroller.framework that builds a static library framework. Build that target, which will produce a BRScroller.framework bundle at the root project directory. Copy that framework into your project and add it as a build dependency.

You must also add the following linker build dependencies, which you can do by clicking the + button in the Link Binary With Libraries section of the Build Phases tab in the project settings:

• QuartzCore.framework

Next, add -ObjC as an Other Linker Flags build setting.

Finally, you'll need to add the path to the directory containing the BRScroller.framework bundle as a Framework Search Paths value in the Build Settings tab of the project settings.

via dependent project

The other way you can integrate BRScroller into your project is to add the BRScroller Xcode project as a dependent project of your project. The BRScroller Xcode project includes a target called BRScroller that builds a static library. You can use that target as a dependency in your own project. The BRScrollerDemo project is set up this way.

To do this, drag the BRScroller.xcodeproj onto your project in the Project Navigator. Then go to the Build Phases tab of your project's settings. Expand the Target Dependencies section and click the + button. You should see the BRScroller static library target as an available option. Select that and click the Add button.

You must also add the following linker build dependencies, which you can do by clicking the + button in the Link Binary With Libraries section of the Build Phases tab in the project settings:

• QuartzCore.framework

Next, add -ObjC as an Other Linker Flags build setting.

Finally, you'll need to add the path to the directory containing the BRScroller.xcodeproj file as a Header Search Paths value in the Build Settings tab of the project settings. If you have added BRScroller as a git submodule to your own project, then the path might be something like "$(PROJECT_DIR)/../BRScroller".

More detailed information on Xcode dependent projects can be found online, for example here or here.