9 thoughts on “Structure your UITableView better with structs and enums in Swift”

1. Hi,
   That’s a very good article. We could even enhance the code à little more ti have à really DRY code.

   For instance this code :
   // MARK: – Public properties
   var stock: Stock? {
   didSet {
   if currency == GlobalSettings.sharedStore.portfolioCurrency {

   sections = [
   Section(type: .General, items: [.NumberOfShares, .DatePurchase]),
   Section(type: .Price, items: [.PricePurchase, .PriceCurrent]),
   Section(type: .Intraday, items: [.IntradayValue, .IntradayPercentage]),
   Section(type: .Valuation, items: [.ValuationPurchase, .ValuationCurrent]),
   Section(type: .GainOrLoss, items: [.GainOrLossValue, .GainOrLossPercentage])
   ]

   } else { // currency != GlobalSettings.sharedStore.portfolioCurrency

   sections = [
   Section(type: .General, items: [.NumberOfShares, .DatePurchase]),
   Section(type: .Price, items: [.PricePurchase, .PriceCurrent]),
   Section(type: .Intraday, items: [.IntradayValue, .IntradayPercentage]),
   Section(type: .CurrencyRate, items: [.CurrencyRatePurchase, .CurrencyRateCurrent]),
   Section(type: .Valuation, items: [.ValuationPurchase, .ValuationCurrent]),
   Section(type: .GainOrLoss, items: [.GainOrLossValue, .GainOrLossPercentage])
   ]
   }
   }
   }

   Could have been like this :

   // MARK: – Public properties
   var stock: Stock? {
   didSet {
   sections.append(Section(type: .General, items: [.NumberOfShares, .DatePurchase]))
   sections.append(Section(type: .Price, items: [.PricePurchase, .PriceCurrent]))
   sections.append(Section(type: .Intraday, items: [.IntradayValue, .IntradayPercentage]))

   if currency == GlobalSettings.sharedStore.portfolioCurrency {
   sections.append(Section(type: .CurrencyRate, items: [.CurrencyRatePurchase, .CurrencyRateCurrent]))
   }

   sections.append(Section(type: .Valuation, items: [.ValuationPurchase, .ValuationCurrent]))
   sections.append(Section(type: .GainOrLoss, items: [.GainOrLossValue, .GainOrLossPercentage]))
   }
   }

   Cheers !

   Répondre

   1. That’s a very good point. Thank you!

      Répondre

2. This is very interesting. We already do that here in our code but in more deeper way.
   For example you could use function inside the enums, and within those functions do the switch case around self. In the end your view controller could look like this:

   override func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {

   return sections[section].type.title()
   }

   Répondre

3. Great idea! I followed a similar approach in Objective-C with the NS_ENUM macro.

   One more step in DRYing up your cell creation method is to use a presenter. Have your method create the cell then pass in the object and cell to a presenter object.

   To make this work the object will need to conform to a protocol. This protocol will have to getters, title and detail for example, that return the strings. Then the presenter can naively pass the corresponding attribute to the cell’s labels.

   Répondre

4. It’s a good article, I like it very much!
   I’ve think around table view’s data structure many times,
   And I can give another solution, the idea comes from CS193p,
   , like this:

   class DataSourceAndDelegate: NSObject, UITableViewDataSource, UITableViewDelegate {

   var sections: [(sectionInfo: SectionInfo, cellInfos: [CellInfo])] = [] { didSet { tableView.reloadData() } }

   weak var tableView: UITableView! { didSet { tableView.dataSource = self; tableView.delegate = self } }

   var reuseIdentifierForCellInfo: ((CellInfo) -> String)!
   var configureCellForCellInfo: ((UITableViewCell, CellInfo) -> Void)?
   var titleForSectionInfo: ((SectionInfo) -> String?)?
   var didSelectCellInfo: ((CellInfo) -> Void)?

   func numberOfSectionsInTableView(tableView: UITableView) -> Int {
   return sections.count
   }

   func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
   return sections[section].cellInfos.count
   }

   func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
   let cellInfo = cellInfoAtIndexPath(indexPath)
   let cell = tableView.dequeueReusableCellWithIdentifier(reuseIdentifierForCellInfo(cellInfo))!
   configureCellForCellInfo?(cell, cellInfo)
   return cell
   }

   func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
   return titleForSectionInfo?(sections[section].sectionInfo)
   }

   // Helper
   func cellInfoAtIndexPath(indexPath: NSIndexPath) -> CellInfo {
   return sections[indexPath.section].cellInfos[indexPath.item]
   }

   func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
   tableView.deselectRowAtIndexPath(indexPath, animated: true)
   let cellInfo = cellInfoAtIndexPath(indexPath)
   didSelectCellInfo?(cellInfo)
   }
   }

   And in ViewController use it like this:
   class ViewController: UIViewController {

   @IBOutlet weak var tableView: UITableView! { didSet { dataSourceAndDelegate.tableView = tableView } }

   var dataSourceAndDelegate = DataSourceAndDelegate()

   override func viewDidLoad() {
   super.viewDidLoad()
   setupDataSourceAndDelegate()
   }

   func setupDataSourceAndDelegate() {
   dataSourceAndDelegate.sections = [
   (.OverView, [
   .Name,
   .Detail,
   .Time]),
   (.Author, [
   .AuthorName,
   .AuthorImage,
   .AuthorAge]),
   (.Footer, [
   .LikeNumber,
   .FollowNumer])
   ]

   dataSourceAndDelegate.reuseIdentifierForCellInfo = {
   cellInfo in
   return « cell »
   }

   dataSourceAndDelegate.configureCellForCellInfo = {
   cell, cellInfo in
   cell.textLabel?.text = cellInfo.rawValue
   }

   dataSourceAndDelegate.titleForSectionInfo = {
   sectionInfo in
   return sectionInfo.rawValue
   }

   dataSourceAndDelegate.didSelectCellInfo = {
   cellInfo in
   print(« did Select: \(cellInfo.rawValue) »)
   }
   }

   enum SectionInfo: String {
   case OverView
   case Author
   case Footer
   }

   enum CellInfo: String {
   case Name
   case Detail
   case Time

   case AuthorName
   case AuthorImage
   case AuthorAge

   case LikeNumber
   case FollowNumer
   }
   }

   DataSourceAndDelegate change table view’s delegate base API to block base API, And in ViewController we only provide minimal configuration to table view, the cell is configured from cell enum, section is configured from section enum.

   Cheers !

   Répondre

5. Sorry the code above not show placeholder type defined on DataSourceAndDelegate which is « SectionInfo » and « CellInfo ».
   DataSourceAndDelegate is like a swift Dictionary when you init it, should give two specific Type.

   Répondre

6. Absolutely stunning…exactly what I searched Google hoping to find!
   Thank you! 🙂

   I’ll likely write up a blog post about implementing this some time and link back to your site. 😀

   Répondre
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