A tableview with Swifty style

SwiftyTableView.swift

import UIKit

// Reference: https://medium.com/swift-programming/upgrade-your-tableviews-with-loading-state-in-swift-1fdce34ada77#.w4sg0dwhk

class SwiftyTableView: UIViewController, UITableViewDelegate, UITableViewDataSource {

    let tableView: UITableView = UITableView()
    let activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView()
    var tableState = TableState<String>.Loading {
        didSet {
            self.tableView.reloadData()
            if tableState.loading() {
                self.activityIndicator.startAnimating()
            } else {
                self.activityIndicator.stopAnimating()
            }
        }
    }


    override func viewDidLoad() {
        super.viewDidLoad()

        tableState = .Loading

        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 2) {
            self.tableState = .Error
        }

        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 3) {
            self.tableState = .Items(["ad", "asdasd", "asd12312", "12313", "adad", "adasdas13", "123wfsdf"])
        }


        tableView.translatesAutoresizingMaskIntoConstraints = false
        activityIndicator.translatesAutoresizingMaskIntoConstraints = false
        tableView.delegate = self
        tableView.dataSource = self
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
        self.view.addSubview(tableView)
        self.view.addSubview(activityIndicator)

        activityIndicator.hidesWhenStopped = true
        activityIndicator.color = .red

        let views = ["tableView": tableView]

        self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-64-[tableView]|", options: [], metrics: nil, views: views))
        self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[tableView]|", options: [], metrics: nil, views: views))
        self.view.addConstraint(NSLayoutConstraint(item: self.activityIndicator, attribute: .centerX, relatedBy: .equal, toItem: self.view, attribute: .centerX, multiplier: 1.0, constant: 0.0))
        self.view.addConstraint(NSLayoutConstraint(item: self.activityIndicator, attribute: .centerY, relatedBy: .equal, toItem: self.view, attribute: .centerY, multiplier: 1.0, constant: 0.0))
        activityIndicator.startAnimating()


    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return tableState.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
        cell.textLabel?.text = tableState.value(for: indexPath.row)
        return cell
    }

}

protocol LoadingTableProtocol {
    associatedtype CustomLoadingType

    func value() -> CustomLoadingType
    static func errorValue() -> CustomLoadingType
    static func loadingValue() -> CustomLoadingType
}


enum TableState<T: LoadingTableProtocol> {
    case Error
    case Loading
    case Items([T])

    var count: Int {
        switch self {
        case .Items(let stringCollection):
            return stringCollection.count
        default:
            return 1
        }
    }

    func value(for row: Int) -> T.CustomLoadingType {
        switch self {
        case .Error:
            return T.errorValue()
        case .Loading:
            return T.loadingValue()
        case .Items(let stringCollection):
            let item = stringCollection[row]
            return item.value()
        }
    }

    func loading() -> Bool {
        switch self {
        case .Loading:
            return true
        default:
            return false
        }
    }
}

extension String: LoadingTableProtocol {

    typealias CustomLoadingType = String

    static func errorValue() -> CustomLoadingType {
        return "Error"
    }

    static func loadingValue() -> CustomLoadingType {
        return "Loading......"
    }

    func value() -> CustomLoadingType {
        return self
    }
}