Lightweight and beautiful wrapper around the official UICollectionView API written in pure Swift.

What is PulsarKit?

PulsarKit is a simple and beautiful wrapper around the official UICollectionView API written in pure Swift. PulsarKit is a library that lets you populate and update collection views simply using your models.

This framework is lightly inspire by Lighter view controllers and UITableViewSource and UICollectionViewSource in Xamarin Platform.

Contents

• Introduction
• Features Highlights
• Requirements
• Communication
• Installation
• Usage
  • Basic usage
  • Event handling
  • Sizing cells
  • Plugins
• Author
• License

Introduction

Never implement UICollectionViewDataSource, UICollectionViewDelegate and UICollectionViewDelegateFlowLayout again.

PulsarKit is a small, focused library that lets you populate and update UICollectionView views from your models. Forget about dequeuing and type casting cells. Forget about converting an IndexPath to a model object. PulsarKit will hand you dequeued views of the correct type along with the right model object for the index path. You can focus on applying your custom data to your custom view.

Features Highlights

• [x] No more UICollectionViewDataSource/UICollectionViewDelegate
• [x] Fluent interface configuration (.when(Model).use(Cell))
• [x] Easy section and row insertion, updation, deletion and movement (source.add(model: ...))
• [x] Easy reordering of collection view cells and sections
• [x] Easy and fine grained row event handling (.on.didSelect)
• [x] Ready to use view controllers
• [x] Powerful plugin system

Requirements

PulsarKit 1.3.x is compatible with:

• Swift 5.0+
• iOS 10+
• Xcode 10.2+

Communication

• If you need help with an PulsarKit feature, open an issue.
• If you'd like to discuss a feature request, open an issue.
• If you found a bug, open an issue. The more detail the better!
• If you need to find or understand an API, check our documentation or Apple's documentation for UICollectionView, on top of which PulsarKit is built.
• If you want to contribute, submit a pull request.

Installation

PulsarKit is available through CocoaPods. CocoaPods is a dependency manager for Cocoa projects. You can install it with the following command:

$ gem install cocoapods

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

source 'https://github.com/CocoaPods/Specs.git'
platform :ios, '10.0'
use_frameworks!

target '<target>' do
pod 'PulsarKit'
end

Then, run the following command:

$ pod install

Usage

In order to use PulsarKit it is necessary to follow 5 simply steps:

1. Conform your models to the Hashable protocol
2. Conform your cells or models to the Bindable protocol
3. Initialize a new instance of CollectionSource
4. Register cells classes
5. Populate the source with your models

The CollectionSource is the main class that manages the state of the UICollectionView. All that is required is to initialize a source with an instance of UICollectionView.

Basic usage

Example with Bindable cells

import PulsarKit

// 1. Conform your models to the `Hashable` protocol
struct User: Hashable {
   let id: String
   let name: String
}

// your custom cell class
class UserCollectionViewCell: UICollectionViewCell {
   @IBOutlet weak var nameLabel: UILabel!
}

// 2. Conform your cells to the `Bindable` protocol
extension UserCollectionViewCell: Bindable {
    func bind(to element: User) {
        nameLabel.text = element.name
    }
}

class MyViewController: UIViewController {
   @IBOutlet weak var collectionView: UICollectionView!

   // 3. Initialize a new instance of `CollectionSource`
   lazy var source = CollectionSource(container: collectionView)

   override func viewDidLoad() {
       super.viewDidLoad()
        
       // 4. Register cells classes
       // the code below tells source to show a `UserCollectionViewCell`
       // for every instance of `User` you add to source.
       source.when(User.self).use(UserCollectionViewCell.self).withCellBinder()

      // fetch users
      fetchUsersFromNetwork()
   }

   func fetchUsersFromNetwork() {
      userProvider.loadAll { [weak self] (users: [User]) in

         // 5. Populate the source with your models
         self?.source.add(models: users)
         self?.source.update()
      }
   }
}

Example with Bindable models

import PulsarKit

// 1. Conform your models to the `Hashable` protocol
struct Order: Hashable {
   let id: String
   let number: Int
}

// 2. Conform your models to the `Bindable` protocol
extension Order: Bindable {
   func bind(to element: OrderCollectionViewCell) {
      element.numberLabel.text = "\(number)"
   }
}

// your cell class
class OrderCollectionViewCell: UICollectionViewCell {
   @IBOutlet weak var numberLabel: UILabel!
}

class MyViewController: UIViewController {
   @IBOutlet weak var collectionView: UICollectionView!

   // 3. Initialize a new instance of `CollectionSource`
   lazy var source = CollectionSource(container: collectionView)

   override func viewDidLoad() {
       super.viewDidLoad()
        
       // 4. Register cells classes
       // the code below tells source to show a `OrderCollectionViewCell`
       // for every instance of `Order` you add to source.
       source.when(Order.self).use(OrderCollectionViewCell.self).withModelBinder()

      // fetch order
      fetchOrders()
   }

   func fetchOrders() {
      orderProvider.loadAll { [weak self] (orders: [Order]) in

         // 5. Populate the source with your models
         self?.source.add(models: orders)
         self?.source.update()
      }
   }
}

Event Handling

Cell selection

let user1 = User(id: 1, name: "Guest") 
let descriptor = source.when(User.self).use(UserCollectionViewCell.self).withCellBinder()

// the callback is called when user did tap on any cell of type `UserCollectionViewCell`
descriptor.on.didSelect { context in
   print("model: \(context.model)")
   print("indexPath: \(context.indexPath)")
}

// the callback is callend when user did tap on a cell `binded` with a specific instance of user
descriptor.on(model: user1).didSelect { context in
   print("model: \(context.model)")
   print("indexPath: \(context.indexPath)")
}

// the callback is callend when user did tap on any cell
source.on.didSelect { _ in
   print("model: \(context.model)")
   print("indexPath: \(context.indexPath)")
}

Other events

let descriptor = source.when(User.self).use(UserCollectionViewCell.self).withCellBinder()

// the callback is called when before adding a cell to collection view
descriptor.on.willDisplay { context in
   print("cell: \(context.cell)")
   print("model: \(context.model)")
   print("indexPath: \(context.indexPath)")
}

Sizing cells

PulsarKit supports different kind of cell sizing. You can provide your custom sizing implementing Sizable protocol. By default PulsarKit uses the TableSize layout that uses autolayout to calculate height and the width of collection view as width of the cell.

PulsarKit has 6 ready-to-use sizes:

• AutolayoutSize: uses autolayout to evaluate the width and the height of the cell
• ContainerSize: uses the collection view bounds as cell size
• TableSize: uses autolayout for height and collection view bounds for width
• SegmentedSize: divides the collection view bounds size into equal parts
• FixedSize: provide a fixed height/width for all cell types (faster if you plan to have all cell sized same)
• CompositeSize: a special size that evaluates combinations of two sizes

Fixed sizing

let descriptor = source.when(User.self).use(UserCollectionViewCell.self).withCellBinder()

// fixed cell sizing
let fixed = FixedSize(width: 40, height: 50)

// set to descriptor
descriptor.set(sizeable: fixed)

Composite sizing

let descriptor = source.when(User.self).use(UserCollectionViewCell.self).withCellBinder()

// sizing composition
let container = ContainerSize() 	// it uses collection view bounds
let fixed = FixedSize(height: 50) 	// fixed height size
let composite = CompositeSize(widthSize: container, heightSize: fixed)  

// set to descriptor
descriptor.set(sizeable: composite)

Custom sizing

import PulsarKit

class MyCustomSize: Sizable {
   public func size<View: UIView>(for view: View, descriptor: Descriptor, model: AnyHashable, in container: UIScrollView) -> CGSize {
      // your custom logic here
   }
}

// ....

let descriptor = source.when(User.self).use(UserCollectionViewCell.self).withCellBinder() 
descriptor.set(sizeable: MyCustomSize())

Sizing for a specific model

// your models instances
let user1 = User(id: 1, name: "John")
let user2 = User(id: 1, name: "Jim")

let descriptor = source.when(User.self).use(UserCollectionViewCell.self).withCellBinder() 

// set to descriptor
descriptor.set(sizeable: FixedSize(width: 300, height: 50), for: user1) // <- user 1
descriptor.set(sizeable: FixedSize(width: 50, height: 320), for: user2) // <- user 2

Plugins

PulsarKit has a powerful plugin system that allows you to add new features and behaviors. You can provide your custom plugin implementing SourcePlugin protocol.

PulsarKit has 4 ready-to-use plugins:

• PageControlPlugin: mantains in sync the UICollectionView pages and UIPageControl
• KeyboardHandlerPlugin: prevents issues of keyboard sliding up and cover UITextField/UITextView inside a cell
• InfiniteScrollingPlugin: enables infinite scrolling handling
• GroupedCollectionPlugin: mimics grouped table view style behavior

Plugin usage example

var infinite = InfiniteScrollingPlugin { source in
	self.fetchMoreUsers { (users: [User]) in
    	self.source.add(models: users)
        self.source.update()
    }
}

source.add(plugin: infinite)

Author

Massimo Oliviero, [email protected]

License

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