[Question]: Replacement for passing Array by reference?

**Background:**

I designed a `TableViewDataSource` class that provides an implementation for `UITableViewDataSource` and `UITableViewDelegate`. You instantiate `TableViewSection` objects, which are passed to the `TableViewDataSource` which are used to configure cells, section headers, handle selection, row insertion, etc.

The `TableViewSection` object has a property called `dataSource: [AnyObject]?`, which, when set, is used to calculate the number of rows in the section, and provide an object for the cell configuration block:

// get the section, dequeue a cell for that section, retrieve the item from the dataSource // ... tableSection.cellConfigurationBlock?(cell: AnyObject, item: AnyObject?, indexPath: NSIndexPath) return cell

What I'd like to do is assign a reference to an array from my `viewModel` to my `tableSection.dataSource`, having my `viewModel` update the array, in turn updating the table view. In Swift, you cannot pass an array by reference. The workaround seems to be to use an `NSMutableArray`, but with that comes a loss of type safety, and greater cognitive load while translating objects back and forth from Swift to Foundation.

**Working Example:**

let kCellIdentifier = "SomeCellIdentifier" class MyViewController: UITableViewController { // Property declarations @IBOutlet var tableDataSource: TableViewDataSource!

var viewModel: MyViewControllerViewModel = MyViewControllerViewModel()

override func viewDidLoad() { super.viewDidLoad()

self.setupTableView() self.refresh() }

func setupTableView() { var tableSection = TableViewSection(cellIdentifier: kCellIdentifier) tableSection.dataSource = self.viewModel.collection // tableSection configuration // ...

self.tableDataSource.addSection(tableSection) }

func refresh() { self.viewModel .refresh() .subscribeNext({ result in self.tableView.reloadData() }, error: { error in self.logger.error(error.localizedDescription) }) } }

The `refresh()` method on the `viewModel` hits my API service, updates it's `collection` property on response, and provides the result on the `next` event of an `RACSignal` (`RACSignal` is a class provided by [Reactive Cocoa](https://github.com/ReactiveCocoa/ReactiveCocoa) and really, besides the point).

I've found one workaround, which involves reassigning the data source each time a single update is made, or after a batch update.

func refresh() { self.viewModel .refresh() .subscribeNext({ result in self.updateDataSource() self.tableView.reloadData() }, error: { error in self.logger.error(error.localizedDescription) }) }

func updateDataSource() { self.tableDataSource.tableSectionForIndex(0)?.dataSource = viewModel.collection }

This approach works, but only temporarily as a workaround. As a `TableViewDataSource` grows and becomes more complex, this method becomes increasingly more complex with imperative, procedural code, the opposite of what I set out to achieve when writing the class.

**Question**

Is there any workaround to stick to native Swift `Array`'s to achieve the equivalent of passing a Foundation `NSArray` or `NSMutableArray` by reference?

**Bonus Question**

Can someone provide me with some class/struct design tips to accomplish the desired goal in pure Swift?

EDIT: 08/27/14 14:30 Added working example and some more details.