PAT used as type

pat.swift

class PersonCell: UICollectionViewCell {
    @IBOutlet weak var firstLabel: UILabel!
    @IBOutlet weak var secondLabel: UILabel!
}

struct Person {
    let firstName: String
    let lastName: String
}

protocol PersonsDatasourceProtocol: class {
    associatedtype Model
    associatedtype Cell: UICollectionViewCell
    
    func didSelect(model: Model)
    func indexPath(for cell: Cell) -> IndexPath?
    func reloadUI()
}

class PersonsDatasource<Model, Cell: UICollectionViewCell>: UICollectionViewDataSource, UICollectionViewDelegate {
    
    var models: [Model] = [] // will be loaded from an api
    weak var delegate: PersonsDatasourceProtocol<Model, Cell>?  // not possible
    
    typealias CellConfigurator = (Model, Cell) -> Void
    private let cellConfigurator: CellConfigurator
    
    init(cellConfigurator: @escaping CellConfigurator) {
        self.cellConfigurator = cellConfigurator
    }
    
    // datasource and delegate methods
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let model = self.models[indexPath.item]
        delegate?.didSelect(model: model)
    }
}

class PersonsViewController: UIViewController, PersonsDatasourceProtocol {
    typealias Model = Person
    typealias Cell = PersonCell
    
    @IBOutlet weak var collectionView: UICollectionView!
    
    let datasource = PersonsDatasource<Model, Cell>(cellConfigurator: { model, cell in
        cell.firstLabel.text = model.firstName
        cell.secondLabel.text = model.lastName
    })
    
    func didSelect(model: Model) {
        // do something with the model ...
    }
    
    func indexPath(for cell: Cell) -> IndexPath? {
        return collectionView.indexPath(for: cell)
    }
    
    func reloadUI() {
        collectionView.reloadData()
    }
}