Dynamic datasource/delegates for UITableView in 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
}

Aleš Kocur · Accepted Answer · 2015-09-27 09:47:21Z

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
}

Yevhen Dubinin · Accepted Answer · 2015-09-27 09:53:07Z

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.

I had to create a new class to make it work. This works too but I am accepting the other one as it was posted earlier, wish I could upvote.

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