not able to load data with ViewModel - swift

Question

the tableView dataSource is properly set up in the IB
the viewController identity is properly set as well in the IB
this is my viewModel
class StatusCodeViewModel {
let apiClient = APIClient.shared
var statusCodes: [StatusCode] = []
let identifier = "statusCodeCell"
init() {}
func loadStatusCodes() {
apiClient.execute(service: .statusCode) { statusCodes in
self.statusCodes = statusCodes
}
}
}
and the viewController in which I want to load data
class ViewController: UIViewController {
#IBOutlet weak var tableView: UITableView!
var viewModel: StatusCodeViewModel? {
didSet {
if viewModel!.statusCodes.count > 0 {
self.tableView.reloadData()
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
viewModel = StatusCodeViewModel()
viewModel!.loadStatusCodes()
}
}
extension ViewController : UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let statusCodes = viewModel!.statusCodes as? [StatusCode] {
return statusCodes.count
}
return 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: viewModel!.identifier)
cell?.textLabel!.text = viewModel!.statusCodes[indexPath.row].title
return cell!
}
}
the data count is 0 and no data is shown in the tableView

Answer 1

You have did set on view model which will occur on initialisation.
You will have to implement some kind of callback when the api returns the call - easiest way would be protocol.
protocol StatusCodeViewModelDelegate {
func callFinished()
}
class StatusCodeViewModel {
let apiClient = APIClient.shared
var statusCodes: [StatusCode] = []
let identifier = "statusCodeCell"
var delegate : StatusCodeViewModelDelegate?
init() {}
func loadStatusCodes() {
apiClient.execute(service: .statusCode) { statusCodes in
self.statusCodes = statusCodes
delegate?.callFinished()
}
}
}
Then in your viewController:
override func viewDidLoad() {
super.viewDidLoad()
viewModel = StatusCodeViewModel()
viewModel.delegate = self
viewModel!.loadStatusCodes()
}
func callFinished() {
self.tableView.reloadData()
}
Don't forget to extend for delegate you just made:
class ViewController: UIViewController, StatusCodeViewModelDelegate {
Or, as #rmaddy suggested, in View model change loadStatusCodes to:
func loadStatusCodes(completion: #escaping () -> Void) {
apiClient.execute(service: .statusCode) { statusCodes in
self.statusCodes = statusCodes
}
}
Then, in the viewDidLoad:
override func viewDidLoad() {
super.viewDidLoad()
viewModel = StatusCodeViewModel()
viewModel!.loadStatusCodes {
self.tableView.reloadData()
}
}

Answer 2

//This would do !
func loadStatusCodes(completion: #escaping () -> Void) {
apiClient.execute(service: .statusCode) { statusCodes in
self.statusCodes = statusCodes
completion()
}
}
// And in ViewController:
override func viewDidLoad() {
super.viewDidLoad()
viewModel = StatusCodeViewModel()
viewModel?.loadStatusCodes() {
self.tableView.reloadData()
}
}