GenericDataSource

A generic small reusable components for data source implementation for UITableView/UICollectionView written in Swift.

Features

BasicDataSource easily bind model to cells with automatic dequeuing.
SegmentedDataSource easily build segmented controls or for empty state of your UICollectionView/UITableView data source.
CompositeDataSource builds complex cells/models structure with easy to use components (BasicDataSource SegmentedDataSource or other CompositeDataSource).
UICollectionView supplementary, UITableView header, and footer views support.
Ability to override any data source method from UIKit classes.
Comprehensive Unit Test Coverage.
Complete Documentation

Requirements

iOS 8.0+
Xcode 10
Swift 4.0+

Installation

CocoaPods

To integrate GenericDataSource into your Xcode project using CocoaPods, specify it in your Podfile:

pod 'GenericDataSources'

IMPORTANT: The pod name is GenericDataSources with "s" at the end.

Carthage

To integrate GenericDataSource into your Xcode project using Carthage, specify it in your Cartfile:

github "GenericDataSource/GenericDataSource"

Manually

Add GenericDataSource.xcodeproj to your project file by drag and drop.

You can then consult to Adding an Existing Framework to a Project.

Example

Basic Data Source Example

UITableView

Create a basic data source and bind it to to a table view.

let dataSource = BasicBlockDataSource<Example, BasicTableViewCell>() { (item: Example, cell: BasicTableViewCell, indexPath) -> Void in
    cell.titleLabel?.text = item.title
}

// Need to keep a strong reference to our data source.
self.dataSource = dataSource

// register the cell
tableView.ds_register(cellClass: BasicTableViewCell.self)
// bind the data source to the table view
tableView.ds_useDataSource(dataSource)

dataSource.items =  <<retrieve items>> // Can be set and altered at anytime

That's it! Your first data source is implemented. No dequeuing! no casting! simple and smart.

UICollectionView

Let's now take it to the next level. Suppose after we implemented it, the requirements changed and we need to implement it using UICollectionView.

let dataSource = BasicBlockDataSource<Example, BasicCollectionViewCell>() { (item: Example, cell: BasicCollectionViewCell, indexPath) -> Void in
    cell.titleLabel?.text = item.title
}

// Need to keep a strong reference to our data source.
self.dataSource = dataSource

// register the cell
collectionView.ds_register(cellClass: BasicCollectionViewCell.self)
// bind the data source to the collection view
collectionView.ds_useDataSource(dataSource)

dataSource.items =  <<retrieve items>> // Can be set and altered at anytime

All you need to do is change the cell class and of course the table view to collection view.

Actually this opens the door for so much possibilities. You can inherit from BasicDataSource and implement your custom generic data source that is based on a protocol implemented by the cell and you don't need to repeat the configuration part. You would create data source like that.

let dataSource1 = CustomDataSource<BasicTableViewCell>() // for table view
let dataSource2 = CustomDataSource<BasicCollectionViewCell>() // for collection view

App store Featured Example

Suppose we want to implement the following screen, the App Store featured tab.

If you want to have a look at the complete source code, it is under Example project -> AppStoreViewController.swift.

We will create cells as we do normally.
Now we need to think about DataSources.
It's simple, one data source for each cell type (BasicDataSource).
CompositeDataSource(sectionType: .single) for the table view rows. Since these rows are of different cell types.
SegmentedDataSource for switching between loading and data views.
Bind the SegmentedDataSource data source to the table view and that's it.
See how we think structurally about our UI and data sources instead of one big cell.

One thing we didn't talk about is the UICollectionView of the featured section cells. It's very simple, just BasicDataSource.

See how we can implement the screen in the following code:

Create the cells.

class AppStoreFeaturedSectionTableViewCell: UITableViewCell { ... }
class AppStoreQuickLinkLabelTableViewCell: UITableViewCell { ... }
class AppStoreQuickLinkTableViewCell: UITableViewCell { ... }
class AppStoreFooterTableViewCell: UITableViewCell { ... }
class AppStoreLoadingTableViewCell: UITableViewCell { ... }

Create BasicDataSources.

class AppStoreLoadingDataSource: BasicDataSource<Void, AppStoreLoadingTableViewCell> {
    // loading should take full screen size.
    override func ds_collectionView(_ collectionView: GeneralCollectionView, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return collectionView.size
    }
}
class AppStoreFooterDataSource: BasicDataSource<Void, AppStoreFooterTableViewCell> { ... }
class AppStoreQuickLinkDataSource: BasicDataSource<FeaturedQuickLink, AppStoreQuickLinkTableViewCell> { ...  }
class AppStoreFeaturedAppsDataSource: BasicDataSource<FeaturedApp, AppStoreFeaturedAppCollectionViewCell> { ... }
class AppStoreFeaturedAppsSectionDataSource: BasicDataSource<FeaturedSection, AppStoreFeaturedSectionTableViewCell> { ... }
class AppStoreQuickLinkLabelDataSource: BasicDataSource<String, AppStoreQuickLinkLabelTableViewCell> { ... }

Create CompositeDataSource that holds the featured page.

class AppStoreFeaturedPageDataSource: CompositeDataSource {
    init() { super.init(sectionType: .single)] }

    var page: FeaturedPage? {
        didSet {
            // remove all existing data sources
            removeAllDataSources()

            guard let page = page else {
                return
            }

            // add featured apps
            let featuredApps = AppStoreFeaturedAppsSectionDataSource()
            featuredApps.setSelectionHandler(UnselectableSelectionHandler())
            featuredApps.items = page.sections
            add(featuredApps)

            // add quick link label
            let quickLinkLabel = AppStoreQuickLinkLabelDataSource()
            quickLinkLabel.setSelectionHandler(UnselectableSelectionHandler())
            quickLinkLabel.items = [page.quickLinkLabel]
            add(quickLinkLabel)

            // add quick links
            let quickLinks = AppStoreQuickLinkDataSource()
            quickLinks.items = page.quickLinks
            add(quickLinks)

            // add footer
            let footer = AppStoreFooterDataSource()
            footer.setSelectionHandler(UnselectableSelectionHandler())
            footer.items = [Void()] // we add 1 element to show the footer, 2 elements will show it twice. 0 will not show it.
            add(footer)
        }
    }
}

Create the outer most data source.

class AppStoreDataSource: SegmentedDataSource {

    let loading = AppStoreLoadingDataSource()
    let page = AppStoreFeaturedPageDataSource()

    // reload data on index change
    override var selectedDataSourceIndex: Int {
        didSet {
            ds_reusableViewDelegate?.ds_reloadData()
        }
    }

    override init() {
        super.init()
        loading.items = [Void()] // we add 1 element to show the loading, 2 elements will show it twice. 0 will not show it.

        add(loading)
        add(page)
    }
}

tableView.ds_register(cellNib: AppStoreFeaturedSectionTableViewCell.self)
tableView.ds_register(cellNib: AppStoreQuickLinkLabelTableViewCell.self)
tableView.ds_register(cellNib: AppStoreQuickLinkTableViewCell.self)
tableView.ds_register(cellNib: AppStoreFooterTableViewCell.self)
tableView.ds_register(cellNib: AppStoreLoadingTableViewCell.self)

Set data sources to the collection view.

tableView.ds_useDataSource(dataSource)

Finally set the data when it is available.

  // show loading indicator
  dataSource.selectedDataSourceIndex = 0

  // get the data from the service
  service.getFeaturedPage { [weak self] page in

    // update the data source model
    self?.dataSource.page.page = page

    // show the page
    self?.dataSource.selectedDataSourceIndex = 1
}

There are many benefits of doing that:

Lightweight view controllers.
You don't need to think about indexes anymore, all is handled for us. Only think about how you can structure your cells into smaller data sources.
We can switch between UITableView and UICollectionView without touching data sources or models. Only change the cells to inherit from UITableViewCell or UICollectionViewCell and everything else works.
We can add/delete/update cells easily. For example we decided to add more blue links. We can do it by just adding new item to the array passed to the data source.
We can re-arrange cells as we want. Just move around the add of data sources calls.
Most importantly no if/else in our code.

Check the Examples application for complete implementations.

Attribution

The main idea comes from [WWDC 2014 Advanced User Interfaces with Collection Views] (https://developer.apple.com/videos/play/wwdc2014/232/) written in swift with generics.

Author

Mohamed Afifi, [email protected]

License

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

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