DataSources - SwiftGit

CollectionView

DataSources

October 10, 2023

⚠️ The latest updates is this PR. It changes the difference algorithm to DifferenceKit.

💾 🔜📱 Type-safe data-driven List-UI Framework. (We can also use ASCollectionNode)

Partial updates(insert, delete, move) of UICollectionView/UITableView is important things for fancy UI.
But, It’s hard that synchronous of data and UI.
DataSources will solve this problem.

Features

Data driven update
- Data did change, then will display.
Partial updates, no more calling reloadData
- Smooth and Faster.
- if the count of changes larger than 300, update with non-animation.
Simplified usage
We can use different type each section.
Type-safe
- We can take clearly typed object by IndexPath.
Using Adapter-pattern for List-UI
- For example, We can also use this for ASCollectionNode of Texture. (Demo app includes it)
Reorder by UI operation
This library is not supported moving between section.

Requirements

Swift 4
iOS 9+

Usage (Example)

Conform protocol Diffable


                                              
                                                public protocol Diffable {

associatedtype Identifier : Hashable

var diffIdentifier: Identifier { get }

}


                                              
                                                struct Model : Diffable {
var diffIdentifier: String {

return id

}
let id: String

}

Most Simplified Usage

Define SectionDataController in ViewController


                                              
                                                let collectionView: UICollectionView
let sectionDataController = SectionDataController<Model, CollectionViewAdapter>(

adapter: CollectionViewAdapter(collectionView: self.collectionView),

isEqual: { $0.id == $1.id } // If Model has Equatable, you can omit this closure.

)
var models: [Model] = [] {

didSet {

sectionDataController.update(items: items, updateMode: .partial(animated: true), completion: {

// Completed update

})

}

}
let dataSource = CollectionViewDataSource(sectionDataController: sectionDataController)
dataSource.cellFactory = { _, collectionView, indexPath, model in

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: “Cell”, for: indexPath) as! Cell

cell.label.text = model.title

return cell

}
collectionView.dataSource = dataSource

Semi Manual

Single-Section (UICollectionView)

Define SectionDataController in ViewController


                                              
                                                let collectionView: UICollectionView

var models: [Model]
let sectionDataController = SectionDataController<Model, CollectionViewAdapter>(

adapter: CollectionViewAdapter(collectionView: self.collectionView),

isEqual: { $0.id == $1.id } // If Model has Equatable, you can omit this closure.

)

Bind Models to SectionDataController in ViewController


                                              
                                                var models: [Model] = […] {

didSet {

sectionDataController.update(items: items, updateMode: .partial(animated: true), completion: {

// Completed update

})

}

}

Implement UICollectionViewDataSource in ViewController


                                              
                                                func numberOfSections(in collectionView: UICollectionView) -> Int {

return 1

}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

return sectionDataController.numberOfItems()

}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: “Cell”, for: indexPath) as! Cell

let m = sectionDataController.item(for: indexPath)

cell.label.text = m.title

return cell

}

Multiple-Section (UICollectionView)

Define DataController in ViewController


                                              
                                                let collectionView: UICollectionView

var models: [Model]
let dataController = DataController<CollectionViewAdapter>(adapter: CollectionViewAdapter(collectionView: self.collectionView))

Define Section<T> in ViewController


                                              
                                                let section0 = Section(ModelA.self, isEqual: { $0.id == $1.id })

let section1 = Section(ModelB.self, isEqual: { $0.id == $1.id })

Add Section to DataController

Order of Section will be decided in the order of addition.


                                              
                                                dataController.add(section: section0) // will be 0 of section

dataController.add(section: section1) // will be 1 of section

Bind Models to DataController


                                              
                                                var section0Models: [ModelA] = […] {

didSet {

dataController.update(

in: section0,

items: section0Models,

updateMode: .partial(animated: true),

completion: {
})

}

}
var section1Models: [ModelA] = […] {

didSet {

dataController.update(

in: section1,

items: section1Models,

updateMode: .partial(animated: true),

completion: {
})

}

}

Implement UICollectionViewDataSource


                                              
                                                func numberOfSections(in collectionView: UICollectionView) -> Int {

return dataController.numberOfSections()

}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

return dataController.numberOfItems(in: section)

}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
return dataController.item(

at: indexPath,

handlers: [

.init(section: section0) { (m: ModelA) in

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: “Cell”, for: indexPath) as! Cell

cell.label.text = m.title

return cell

},

.init(section: section1) { (m: ModelB) in

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: “Cell”, for: indexPath) as! Cell

cell.label.text = m.title

return cell

},

])
/* Other way

switch indexPath.section {

case section0:

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: “Cell”, for: indexPath) as! Cell

let m = _dataController.item(at: indexPath, in: section0)

cell.label.text = m.title

return cell

case section1:

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: “Cell”, for: indexPath) as! Cell

let m = _dataController.item(at: indexPath, in: section1)

cell.label.text = m.title

return cell

default:

fatalError()

}

*/

}

Reorder by UI operation

SectionDataController has a snapshot for List-UI. It helps that perform batch update List-UI in safety.

But, the snapshots include side-effects. For example, if we did reorder items of List-UI by UI operation. In this time, Items of List-UI is caused differences to the snapshot. It will be caused unnecessary diff.

Therefore when we reorder items, we should operation followings.

Reorder items of UI
Call SectionDataController.reserveMoved(...
Reorder items of Array
Call SectionDataController.update(items: [T]..

Appendix

Combination with RxSwift

We can use DataControllers with RxSwift. The following code is an example.

Add extension


                                              
                                                import RxSwift

import DataControllers
extension SectionDataController : ReactiveCompatible {}
extension Reactive where Base : SectionDataControllerType {
public func partialUpdate<

T,

Controller: ObservableType

>

(animated: Bool) -> (_ o: Source) -> Disposable where Source.E == [T], T == Base.ItemType {
weak var t = base.asSectionDataController()
return { source in
source

.observeOn(MainScheduler.instance)

.concatMap { (newItems: [T]) -> Completable in

Completable.create { o in

guard let sectionDataController = t else {

o(.completed)

return Disposables.create()

}

sectionDataController.update(items: newItems, updateMode: .partial(animated: animated), completion: {

o(.completed)

})

return Disposables.create()

}

}

.subscribe()

}

}

}


                                              
                                                let models: Variable<[Model]>

let sectionDataController = SectionDataController<Model, CollectionViewAdapter>
models

.asDriver()

.drive(sectionDataController.rx.partialUpdate(animated: true))

Demo Application

This repository include Demo-Application. You can touch DataSources.

Clone repository.


                                              
                                                $ git clone https://github.com/muukii/DataSources.git

$ cd DataSources

$ pod install

Open xcworkspace
Run DataSourcesDemo on iPhone Simulator.

Installation

CocoaPods


                                              
                                                pod ‘DataSources’

Carthage


                                              
                                                github “muukii/DataSources”

You need to add DataSources.framework and DifferenceKit.framework to your project.

GitHub

View Github

#collectionview #datasource #diff #ios #rxswift #uicollectionview #viewcontroller