SourceModel_iOS: A Swift repository from stanwood

SourceModel is a lightweight wrapper for UICollectionViewDataSource/Delegate and UITableViewDataSource/Delegate. It removes the burden of writing the boiler plate code when working with tableViews and collectionViews, allowing you to focus on what's important, populating the cells with data.

SourceModdel focus on Seperation of Concern, where the cell should only be accessible to get the data to present and decide how to present it. The dataSource should not be responsible for deciding how the cell should populate its data, nor know about the view.

Usage

Let's jump into some of the protocols you need to be familiar with, to get started. Let's think of a view, that shows products:

`ModelCollection` protocol

ModelCollection represent a collection of similar items, the products in our case.

public protocol ModelCollection {
    
    /// Returns the number of items
    var numberOfItems: Int { get }
    
    /// Returns the number of sections
    var numberOfSections: Int { get }
    
    /// A subscript to return a type in an indexPath
    subscript(indexPath: IndexPath) -> Model? { get }
    
    /// A subscript to return a collection dataType within a section
    subscript(section: Int) -> ModelCollection { get }
    
    /// Returns the cell type at indexPath
    func cellType(forItemAt indexPath: IndexPath) -> Fillable.Type?
}

`Model` protocol

Model represents a single item in a collection of item, a product.

Both in action

Let's create a collection of items to see it in action:

We will dive into the Fillable protocol in a later stage, for now, let's assume we have a ProductCell.

struct Product { ... }

struct Products: ModelCollection {
    
    let items: [Product]
    
    var numberOfItems: Int {
    	return items.count
    }
    
    var numberOfSections: Int { 
    	return 1
    }
    
    subscript(indexPath: IndexPath) -> Model? { 
    	return items[indexPath.row] 
    }
    
    subscript(section: Int) -> ModelCollection { 
    	return self 
    }
    
    func cellType(forItemAt indexPath: IndexPath) -> Fillable.Type? {
    	return ProductCell.self
    }
}

Ok, this is cool, but we can make it even simpler. SourceModel offers an Elements class that wrapps the above, where you only need to take care of the cells. This is how it works:

class Products: Elements<Product>, Codable {
   func cellType(forItemAt indexPath: IndexPath) -> Fillable.Type? {
    	return ProductCell.self
    }
}

Now that we we finalised our collection, let's create an instance of Products:

let products = Products(items: [Product(), Product()])

`Fillable` protocol

Each cell must conform to the Fillable protocol. This is where your model is injected, and where you will populate the cell.

class ProductCell: UICollectionViewCell, Fillable {

	....
	
	func fill(with model: Model?) {
		guard let product = model as? Product else { return }
		
		/// Handle product
	}
}

Preparing the DataSource and Delegate

Now that we have the model, modelCollection, and the cell, let's create the DataSource and Delegate

class ProductsViewController: UIViewController {
   
   var dataSource: CollectionDataSource! /// Use TableDataSource for UITableView
   var delegate: CollectionDelegate! /// Use TableDelegate for UITableView
   
   let products = Products(items: [Product(), Product()])
   
   override func viewDidLoad() {
      super.viewDidLoad()
      setupCollectionView(with: products)
   }
   
   private func setupCollectionView(with modelCollection: ModelCollection?)
      delegate = CollectionDataSource(modelCollection: modelCollection)
      dataSource = CollectionDelegate(modelCollection: modelCollection)
        
      collectionView.register(cellType: ProductCell.self)
        
      collectionView.delegate = delegate
      collectionView.dataSource = dataSource
   }
}

Note: To get the register(cellType:) function, add StanwoodCore to your project.

That's it! 😊

You are probably wondering where to go from here? Let's look at a more complex cases, and how SourceModel can help you.

Working with `Sections`

Working with sections can be a tedious task. You can use ModelCollection and inject a collection of sections (other ModelCollections). Alternatively, SourceModel offers Sections. Let's look at our Products elements from before, and migrate it to sections of different product categories

class ProductsViewController: UIViewController {
   
   var dataSource: CollectionDataSource! /// Use TableDataSource for UITableView
   var delegate: CollectionDelegate! /// Use TableDelegate for UITableView
   
   let sections: Sections!
   
   override func viewDidLoad() {
      super.viewDidLoad()
      
      let beautyProducts = Products(items: [Product(), Product()])
	   let groceryProducts = Products(items: [Product(), Product()])
	   
	   sections = Sections(sections: [beautyProducts, groceryProducts])
      setupCollectionView(with: products)
   }
   
   private func setupCollectionView(with modelCollection: ModelCollection?)
      delegate = CollectionDataSource(modelCollection: modelCollection)
      dataSource = CollectionDelegate(modelCollection: modelCollection)
        
      collectionView.register(cellType: ProductCell.self)
        
      collectionView.delegate = delegate
      collectionView.dataSource = dataSource
   }
}

Working with `Headers`

If you want to add a section header, make sure you ModelCollection conforms to Headerable. You have a couple of optional options, depending weather you are populating a collectionView or a tableView.

Headerable

/// Headerable protocol to add header support for `UICollectionView` and `UITableView`
@objc public protocol Headerable {
    
    /// `UITableView` section header view
    @objc optional var headerView: UIView { get }
    
    /// `UICollectionView` header reusable header view
    @objc optional var reusableView: UICollectionReusableView { get }
}

Example

Let's take our Products and add a header

class Products: Elements<Product>, Codable, Headerable {
   
   var headerView: UIView { 
   		let view = CategoryHeaderView.loadFromNib()
       view?.backgroundColor = .clear
       view?.set(title: title)
       return view ?? UIView()
   }
   ...
}

Note: To get the loadFromNib() function, add StanwoodCore to your project

Important!

Known issue: At this stage, ModelCollection does not support reusable header views. This is under development. To avoid any memory issues, you should use Headerable only for a single header view.

Implementing `Delegate` pattern

To work with the Delegate Design Pattern, SourceModel offers a Delegateable protocol. Let's see how that works with our ProductCell:

Example: Cell

protocol ProductCellDelegate: class {
	func productCellDidDoSomething(with product: Product)
}

/// Conform to `Delegateable`
class ProductCell: UICollectionViewCell, Fillable, Delegateable {

	private weak var delegate: ProductCellDelegate?
	
	....
	
	/// Set the delegate
	func set(delegate: AnyObject) {
		self.delegate = delegate as? ProductCellDelegate
	}
	
	@IBAction didTapSomeButton(_ sender: UIButton) {
	   delegate?. productCellDidDoSomething(with: product)
	}
}

**Example: ViewController

class ProductsViewController: UIViewController {
   
   var dataSource: CollectionDataSource! /// Use TableDataSource for UITableView
   var delegate: CollectionDelegate! /// Use TableDelegate for UITableView
   
   let products = Products(items: [Product(), Product()])
   
   override func viewDidLoad() {
      super.viewDidLoad()
      setupCollectionView(with: products)
   }
   
   private func setupCollectionView(with modelCollection: ModelCollection?)
   
      delegate = CollectionDataSource(modelCollection: modelCollection)
      
      /// Inject `self` as the delegate
      dataSource = CollectionDelegate(modelCollection: modelCollection, delegate: self)
        
      collectionView.register(cellType: ProductCell.self)
        
      collectionView.delegate = delegate
      collectionView.dataSource = dataSource
   }
}

extension ProductsViewController: ProductCellDelegate {
	
	func productCellDidDoSomething(with product: Product) {
		/// Do something with product
	}
}

Working with cell index's

In some cases, we require to know at what index the cell is positioned. Conform to Indexable protocol to get the index.

Example

class ProductCell: UICollectionViewCell, Fillable, Indexable {
	
	....
	
	func inject(_ indexPath: IndexPath) {
		/// Do something with the index
	}
}

Roadmap

Adding support for delegate patter
Adding support for headers
Adding Indexable protocol to inject the indexPath into the cell
Adding a reloadData(animated:) that reloads the models that changed
Adding generics to Fillable protocol
Adding reusable Header/Footer view
Adding SwiftUI support
Adding Combine support

Please open an issue for feature requests.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Requirements

Installation

SourceModel is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'SourceModel'

Author

Tal Zion, tal.zion@stanwood.de

License

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

stanwood/SourceModel_iOS