Dynamic datasource/delegates for UITableView in swift - swift

Question

I need to set up different objects based on certain conditions as the datasource & delegate for table view.
But I am not able to assign tableview's datasource/delegate as it throws some errors.
Cannot assign a value of type NSObject? to a value of type UITableViewDelegate?
I did check this Q&A but this did not work.
var dataSourceDelegate:NSObject?
class RootViewController: UIViewController {
...
override func viewDidLoad() {
dataSourceDelegate = TableDataSourceDelegate()
// Table View
tableView = UITableView()
tableView!.setTranslatesAutoresizingMaskIntoConstraints(false)
tableView!.dataSource = dataSourceDelegate
// Cannot assign a value of type NSObject? to a value of type UITableViewDataSource?
tableView!.delegate = dataSourceDelegate
// Cannot assign a value of type NSObject? to a value of type UITableViewDelegate?
view.addSubview(tableView!)
// Constraints
var views:[String:UIView] = ["table":tableView!]
var hTableConstraint = "H:|[table]|"
var vConstraint = "V:|[table]|"
view.addConstraintsToView([hTableConstraint, vConstraint], view: view, viewVariables: views)
}
...
}
This is the datasource/delegate class
class TableDataSourceDelegate:NSObject, UITableViewDataSource, UITableViewDelegate {
// MARK: Datasource
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 0
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
return UITableViewCell()
}
// MARK: Delegates
}

Answer 1

NSObject? doesn't conforms to UITableViewDelegate, neither to UITableViewDataSource. You should create your protocol like
protocol GeneralDataSource: UITableViewDataSource, UITableViewDelegate {}
And then all data sources should conform that protocol.
class MyDataSource: NSObject, GeneralDataSource {
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
return UITableViewCell()
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 2
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
}
Then you can use it like this
var myDataSource: GeneralDataSource?
override func viewDidLoad() {
super.viewDidLoad()
self.myDataSource = MyDataSource()
self.tableView.delegate = self.myDataSource
}

Answer 2

This is how your TableDataSourceDelegate should look like:
import UIKit
class TableDataSourceDelegate: NSObject {
}
extension TableDataSourceDelegate: UITableViewDataSource {
#objc func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 0
}
#objc func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.Default, reuseIdentifier: "defaultCell")
cell.textLabel?.text = "test"
return cell
}
}
extension TableDataSourceDelegate: UITableViewDelegate {
// your delegate implementation here
}
And view controller implementation
import UIKit
// The typealias definition
typealias TVDataSourceDelegate = protocol<UITableViewDataSource, UITableViewDelegate>
class ViewController: UIViewController {
var dataSourceDelegate: TVDataSourceDelegate?
var tableView: UITableView?
override func viewDidLoad() {
super.viewDidLoad()
dataSourceDelegate = TableDataSourceDelegate()
// Table View
tableView = UITableView()
tableView!.translatesAutoresizingMaskIntoConstraints = false
tableView!.dataSource = dataSourceDelegate
tableView!.delegate = dataSourceDelegate
view.addSubview(tableView!)
// other code ...
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Although, I would recommend to separate dataSource and delegate objects (e.g. put the delegate protocol conforming code into your view controller's code.