DeltaCalculator is a Swift Library focused on replacing reloadData() calls with animated insert, delete and move operations.
DeltaCalculator tries to optimize the number of iterations to calculate all the changes, making sure the UI thread doesn't block.
This framework is based on BKDeltaCalculator Objective-C library.
DeltaCalculator is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'DeltaCalculator'DeltaCalculator compares two arrays and computes the delta between them, represented by a Delta object.
DeltaCalculator is uses generics, therefor, you need to supply the class in the initializer.
In case your generic class is Equatable you can initialize the calculator without an equalityTest.
let deltaCalculator = DeltaCalculator<String>()
let delta = deltaCalculator.deltaFromOldArray(dataModel, toNewArray: newDataModel)Otherwise you are required to supply an equalityTest in the initializer.
let deltaCalculator = DeltaCalculator<NSDate>() { (lhs, rhs) -> Bool in
return lhs.compare(rhs) == .OrderedSame
}
let delta = deltaCalculator.deltaFromOldArray(dataModel, toNewArray: newDataModel)To apply the Delta to a UITableView you need to use a batch update such as the following:
let delta = deltaCalculator.deltaFromOldArray(dataModel, toNewArray: newDataModel)
tableView.beginUpdates()
dataModel = newDataModel
delta.applyUpdatesToTableView(tableView, inSection: 0, withRowAnimation: UITableViewRowAnimation.Right)
tableView.endUpdates()To apply the Delta to a UICollectionView you also need to perform it in a batch update:
let delta = deltaCalculator.deltaFromOldArray(dataModel, toNewArray: newDataModel)
collectionView.performBatchUpdates({
self.dataModel = newDataModel
delta.applyUpdatesToCollectionView(collectionView, inSection: 0)
}, completion: nil)There is a sample project in the Example directory.
Ivan Bruel, @ivanbruel
Delta is available under the MIT license. See the LICENSE file for more info.