Move navigation actions that don't change the data from view model to view controller.

Author: jaclync

WooCommerce/Classes/ViewRelated/Filters/FilterListViewController.swift

@@ -3,6 +3,9 @@ import UIKit
 /// The view model protocol for filtering a list of models with generic filters.
 ///
 protocol FilterListViewModel {
+    /// The type of the final value returned to the caller of `FilterListViewController`.
+    associatedtype Criteria
+
     // Filter Action UI configuration
 
     /// The title of the Filter CTA at the bottom.
@@ -14,13 +17,10 @@ protocol FilterListViewModel {
     /// Tapping on each filter type row navigates to another list selector for the filter value.
     var filterTypeViewModels: [FilterTypeViewModel] { get }
 
-    // Navigation & Actions
-
-    /// Called when the user taps on the CTA to filter the list with the latest filters.
-    func onFilterActionTapped()
+    /// The final value returned to the caller of `FilterListViewController`.
+    var criteria: Criteria { get }
 
-    /// Called when the user dismisses the filter list screen.
-    func onDismissActionTapped()
+    // Navigation & Actions
 
     /// Called when the user taps on the CTA to clear all filters.
     func onClearAllActionTapped()
@@ -76,12 +76,12 @@ protocol FilterType {
 /// The UI consists of a list of filters at the top and a Filter CTA at the bottom that is always visible to apply the filters.
 /// Tapping on a filter in the list navigates to a list of options for the filter.
 ///
-final class FilterListViewController: UIViewController {
+final class FilterListViewController<ViewModel: FilterListViewModel>: UIViewController {
 
     @IBOutlet private weak var navigationControllerContainerView: UIView!
     @IBOutlet private weak var filterActionContainerView: UIView!
 
-    private let viewModel: FilterListViewModel
+    private let viewModel: ViewModel
     private let listSelectorCommand: FilterListSelectorCommand
 
     private lazy var listSelector: ListSelectorViewController
@@ -94,8 +94,21 @@ final class FilterListViewController: UIViewController {
     private var cancellableSelectedFilterType: ObservationToken?
     private var cancellableSelectedFilterValue: ObservationToken?
 
-    init(viewModel: FilterListViewModel) {
+    private let onFilterAction: (ViewModel.Criteria) -> Void
+
+    // Strings.
+
+    private let navigationBarTitleWithoutActiveFilters =
+        NSLocalizedString("Filters", comment: "Navigation bar title format for filtering a list of products without filters applied.")
+    private let navigationBarTitleFormatWithActiveFilters =
+        NSLocalizedString("Filters (%ld)", comment: "Navigation bar title format for filtering a list of products with filters applied.")
+
+    /// - Parameters:
+    ///   - viewModel: Used to render the filter list selector and the selected filter value list selector.
+    ///   - onFilterAction: Called when the user taps on the Filter CTA.
+    init(viewModel: ViewModel, onFilterAction: @escaping (ViewModel.Criteria) -> Void) {
         self.viewModel = viewModel
+        self.onFilterAction = onFilterAction
         self.listSelectorCommand = FilterListSelectorCommand(data: viewModel.filterTypeViewModels)
         super.init(nibName: "FilterListViewController", bundle: nil)
     }
@@ -123,11 +136,17 @@ final class FilterListViewController: UIViewController {
     // MARK: - Navigation
     //
     @objc func filterActionButtonTapped() {
-        viewModel.onFilterActionTapped()
+        dismiss(animated: true) { [weak self] in
+            guard let self = self else {
+                return
+            }
+            let criteria = self.viewModel.criteria
+            self.onFilterAction(criteria)
+        }
     }
 
     @objc func dismissButtonTapped() {
-        viewModel.onDismissActionTapped()
+        dismiss(animated: true) {}
     }
 
     @objc func clearAllButtonTapped() {
@@ -224,20 +243,13 @@ private extension FilterListViewController {
 
     func updateListSelectorNavigationTitle(numberOfActiveFilters: Int) {
         listSelectorCommand.navigationBarTitle = numberOfActiveFilters > 0 ?
-            String.localizedStringWithFormat(Strings.navigationBarTitleFormatWithActiveFilters, numberOfActiveFilters):
-            Strings.navigationBarTitleWithoutActiveFilters
+            String.localizedStringWithFormat(navigationBarTitleFormatWithActiveFilters, numberOfActiveFilters):
+            navigationBarTitleWithoutActiveFilters
     }
 
     func updateClearAllActionVisibility(numberOfActiveFilters: Int) {
         listSelector.navigationItem.rightBarButtonItem = numberOfActiveFilters > 0 ? clearAllBarButtonItem: nil
     }
-
-    enum Strings {
-        static let navigationBarTitleWithoutActiveFilters =
-            NSLocalizedString("Filters", comment: "Navigation bar title format for filtering a list of products without filters applied.")
-        static let navigationBarTitleFormatWithActiveFilters =
-            NSLocalizedString("Filters (%ld)", comment: "Navigation bar title format for filtering a list of products with filters applied.")
-    }
 }
 
 private extension FilterListViewController {

WooCommerce/Classes/ViewRelated/Products/Filters/FilterProductListViewModel.swift

@@ -3,6 +3,8 @@ import Yosemite
 
 /// `FilterListViewModel` for filtering a list of products.
 final class FilterProductListViewModel: FilterListViewModel {
+    typealias Criteria = Filters
+
     /// Aggregates the filter values that can be updated in the Filter Products UI.
     struct Filters {
         let stockStatus: ProductStockStatus?
@@ -18,20 +20,9 @@ final class FilterProductListViewModel: FilterListViewModel {
     private let productStatusFilterViewModel: FilterTypeViewModel
     private let productTypeFilterViewModel: FilterTypeViewModel
 
-    /// Used to dismiss the Filter Products UI.
-    private let sourceViewController: UIViewController
-
-    typealias FilterCompletion = (_ filters: Filters) -> Void
-    private let onFilterCompletion: FilterCompletion
-
     /// - Parameters:
-    ///   - sourceViewController: the view controller that presents the Filter Products UI, used to dismiss the screen upon user actions.
     ///   - filters: the filters to be applied initially.
-    ///   - onFilterCompletion: called when the user taps the Filter CTA to apply the latest filters to the product list.
-    init(sourceViewController: UIViewController, filters: Filters, onFilterCompletion: @escaping FilterCompletion) {
-        self.sourceViewController = sourceViewController
-        self.onFilterCompletion = onFilterCompletion
-
+    init(filters: Filters) {
         self.stockStatusFilterViewModel = ProductListFilter.stockStatus.createViewModel(filters: filters)
         self.productStatusFilterViewModel = ProductListFilter.productStatus.createViewModel(filters: filters)
         self.productTypeFilterViewModel = ProductListFilter.productType.createViewModel(filters: filters)
@@ -43,21 +34,11 @@ final class FilterProductListViewModel: FilterListViewModel {
         ]
     }
 
-    func onFilterActionTapped() {
-        sourceViewController.dismiss(animated: true) { [weak self] in
-            guard let self = self else {
-                return
-            }
-            let stockStatus = self.stockStatusFilterViewModel.selectedValue as? ProductStockStatus ?? nil
-            let productStatus = self.productStatusFilterViewModel.selectedValue as? ProductStatus ?? nil
-            let productType = self.productTypeFilterViewModel.selectedValue as? ProductType ?? nil
-            let filters = Filters(stockStatus: stockStatus, productStatus: productStatus, productType: productType)
-            self.onFilterCompletion(filters)
-        }
-    }
-
-    func onDismissActionTapped() {
-        sourceViewController.dismiss(animated: true, completion: nil)
+    var criteria: Filters {
+        let stockStatus = stockStatusFilterViewModel.selectedValue as? ProductStockStatus ?? nil
+        let productStatus = productStatusFilterViewModel.selectedValue as? ProductStatus ?? nil
+        let productType = productTypeFilterViewModel.selectedValue as? ProductType ?? nil
+        return Filters(stockStatus: stockStatus, productStatus: productStatus, productType: productType)
     }
 
     func onClearAllActionTapped() {

WooCommerce/Classes/ViewRelated/Products/ProductsViewController.swift

@@ -458,11 +458,11 @@ private extension ProductsViewController {
     }
 
     @objc func filterButtonTapped() {
-        let viewModel = FilterProductListViewModel(sourceViewController: self, filters: filters) { [weak self] filters in
+        let viewModel = FilterProductListViewModel(filters: filters)
+        let filterProductListViewController = FilterListViewController(viewModel: viewModel) { [weak self] filters in
             self?.filters = filters
             // TODO-2037: filter products based on the filters
         }
-        let filterProductListViewController = FilterListViewController(viewModel: viewModel)
         present(filterProductListViewController, animated: true, completion: nil)
     }
 }