ZLBalancedFlowLayout

A UICollectionViewFlowLayout subclass that scales items to take up space, optimized for large item set, inspired by NHBalancedFlowLayout.

zhxnlai
309
21
Swift

ZLBalancedFlowLayout

A UICollectionViewFlowLayout subclass that scales items to take up space, optimized for large item set, inspired by NHBalancedFlowLayout.

Previews

###UICollectionViewScrollDirectionVertical



###UICollectionViewScrollDirectionHorizontal

CocoaPods

You can install ZLBalancedFlowLayout through CocoaPods adding the following to your Podfile:

pod 'ZLBalancedFlowLayout'

CocoaPods’ support for swift is still pre-released, and requires your iOS deployment target to be 8.0 or later:

[sudo] gem install cocoapods --pre

Usage

Checkout the demo app for an example.

ZLBalancedFlowLayout supports all properties of UICollectionViewFlowLayout and the corresponding delegate methods, including minimumLineSpacing, minimumInteritemSpacing, sectionInset, etc.

Use rowHeight to adjust the item height.

/// The ideal row height of items in the grid
var rowHeight = CGFloat(100)

/// The option to enforce the ideal row height by changing the aspect ratio of the item if necessary.
var enforcesRowHeight = false

Benchmarks

ZLBalancedFlowLayout uses dynamic programming techniques to find the optimal partition of cells upfront.
The benchmarks are based on timings of prepareLayout:

###iPhone 6

NumSections NumItemsPerSection ZLBalancedFlowLayout UICollectionViewFlowLayout
1 100 0.0517209768295288 0.00196903944015503
1 1000 0.565874993801117 0.0149750113487244
1 3000 Recursion overflow, not yet tail optimized 0.0408549904823303
10 100 0.523442983627319 0.0157199501991272
10 1000 5.28750801086426 0.130671977996826
100 100 4.89241003990173 0.118210017681122

###iOS simulator

NumSections NumItemsPerSection ZLBalancedFlowLayout UICollectionViewFlowLayout
1 100 0.0160560011863708 0.000555038452148438
1 1000 0.228259027004242 0.0039139986038208
1 3000 1.20643001794815 0.0141730308532715
10 100 0.158486008644104 0.0039370059967041
10 1000 2.26102298498154 0.0399309992790222
100 100 1.60317003726959 0.0364070534706116
100 1000 21.678355038166 0.385994970798492

Requirements

  • iOS 6 or higher.
  • Automatic Reference Counting (ARC).

License

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

Photo Credits

The photos in the demo app are selected from National Geographic