UITableView with MVVM using Swift

MVVM in iOS can be easily implemented without using third party dependencies. For data binding, we can use a simple combination of Closure and didSet to avoid third-party dependencies.

public final class Observable<Value> {

    private var closure: ((Value) -> ())?

    public var value: Value {
        didSet { closure?(value) }
    }

    public init(_ value: Value) {
        self.value = value
    }

    public func observe(_ closure: @escaping (Value) -> Void) {
        self.closure = closure
        closure(value)
    }
}

An example of data binding from ViewController:

final class ExampleViewController: UIViewController {

    private func bind(to viewModel: ViewModel) {
        viewModel.items.observe(on: self) { [weak self] items in
            self?.tableViewController?.items = items
            // self?.tableViewController?.items = viewModel.items.value // This would be Momory leak. You can access viewModel only with self?.viewModel
        }
        // Or in one line:
        viewModel.items.observe(on: self) { [weak self] in self?.tableViewController?.items = $0 }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        bind(to: viewModel)
        viewModel.viewDidLoad()
    }
}

protocol ViewModelInput {
    func viewDidLoad()
}

protocol ViewModelOutput {
    var items: Observable<[ItemViewModel]> { get }
}

protocol ViewModel: ViewModelInput, ViewModelOutput {}
final class DefaultViewModel: ViewModel {  
  let items: Observable<[ItemViewModel]> = Observable([])

  // Implmentation details...
}

Later it can be replaced with SwiftUI and Combine (when a minimum iOS version of your app is 13)

In this article, there is a more detailed description of MVVM https://tech.olx.com/clean-architecture-and-mvvm-on-ios-c9d167d9f5b3

You are doing good job, but you can even improve you product model with adding following function to get array of direct models. It is very useful when you have create array from web Api response.

class Product : NSObject
    {

        var imgUrl : String!
        var name : String!
        var quantity : Int!

        init(dictionary: [String:Any])
        {
            imgUrl = dictionary["img_url"] as? String
            name = dictionary["name"] as? String
            quantity = dictionary["quantity"] as? Int
        }
        init(name: String, image_url: String, quantity: Int)
        {
        self.name = name
        self.imgUrl = image_url
        self.quantity = quantity
        }
        public class func modelsFromArray(array:[[String:Any]]) -> [Product]
        {
            var models:[Product] = []
            for item in array
            {
                models.append(Product.init(dictionary:item))
            }
            return models
        }
    }

With Usage Like

let product1 = Product(name: "Prodcut1", image_url: "", quantity: 2) //Normal Case

    let productList:[[String:Any]] =
        [
        ["name":"Jaydeep","img_url":"xyz","quantity":1],
        ["name":"Jaydeep","img_url":"xyz","quantity":2],
        ["name":"Jaydeep","img_url":"xyz","quantity":3],
        ["name":"Jaydeep","img_url":"xyz","quantity":4],
        ["name":"Jaydeep","img_url":"xyz","quantity":5],
        ["name":"Jaydeep","img_url":"xyz","quantity":6]
        ]
    //Assign Direct Dictionary to Get Array Of Models
/* Very useful when productList is dictionary from server response*/
    let productArray:[Product] = Product.modelsFromArray(array: productList)

And Also your Cell Class is Improved By

class ProductTableViewCell: UITableViewCell {

@IBOutlet weak var productQuantity: UILabel!
@IBOutlet weak var productName: UILabel!
@IBOutlet weak var productImageView: UIImageView!
func setProductData(product:Product)
{
 self.productName.text = product.name
 self.productQuantity.text = "\(product.quantity)"

}

}

Usage:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: PRODUCT_CELL_IDENTIFIER) as! ProductTableViewCell
    let product = productViewModel.productsArray[indexPath.row]
    cell.setProductData(product:product)
    return cell
  }