Merge pull request #2270 from woocommerce/issue/2037-filter-products-discard-changes

Show discard changes prompt when dismissing filter products screen with filter changes

Author: jaclync

WooCommerce/Classes/ViewRelated/Filters/FilterListViewController.swift

@@ -4,7 +4,7 @@ import UIKit
 ///
 protocol FilterListViewModel {
     /// The type of the final value returned to the caller of `FilterListViewController`.
-    associatedtype Criteria
+    associatedtype Criteria: Equatable
 
     // Filter Action UI configuration
 
@@ -82,6 +82,7 @@ final class FilterListViewController<ViewModel: FilterListViewModel>: UIViewCont
     @IBOutlet private weak var filterActionContainerView: UIView!
 
     private let viewModel: ViewModel
+    private let originalCriteria: ViewModel.Criteria
     private let listSelectorCommand: FilterListSelectorCommand
 
     private lazy var listSelector: ListSelectorViewController
@@ -108,6 +109,7 @@ final class FilterListViewController<ViewModel: FilterListViewModel>: UIViewCont
     ///   - onFilterAction: Called when the user taps on the Filter CTA.
     init(viewModel: ViewModel, onFilterAction: @escaping (ViewModel.Criteria) -> Void) {
         self.viewModel = viewModel
+        self.originalCriteria = viewModel.criteria
         self.onFilterAction = onFilterAction
         self.listSelectorCommand = FilterListSelectorCommand(data: viewModel.filterTypeViewModels)
         super.init(nibName: "FilterListViewController", bundle: nil)
@@ -146,6 +148,13 @@ final class FilterListViewController<ViewModel: FilterListViewModel>: UIViewCont
     }
 
     @objc func dismissButtonTapped() {
+        if hasFilterChanges() {
+            UIAlertController.presentDiscardChangesActionSheet(viewController: self, onDiscard: { [weak self] in
+                self?.dismiss(animated: true) {}
+            })
+            return
+        }
+
         dismiss(animated: true) {}
     }
 
@@ -255,6 +264,14 @@ private extension FilterListViewController {
     }
 }
 
+// MARK: Private helpers
+//
+private extension FilterListViewController {
+    func hasFilterChanges() -> Bool {
+        return viewModel.criteria != originalCriteria
+    }
+}
+
 private extension FilterListViewController {
     final class FilterListSelectorCommand: ListSelectorCommand {
         typealias Cell = SettingTitleAndValueTableViewCell

WooCommerce/Classes/ViewRelated/Filters/FilterListViewController.xib

@@ -21,14 +21,14 @@
             <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
             <subviews>
                 <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" translatesAutoresizingMaskIntoConstraints="NO" id="0Hi-U6-ohm">
-                    <rect key="frame" x="0.0" y="44" width="414" height="818"/>
+                    <rect key="frame" x="0.0" y="0.0" width="414" height="862"/>
                     <subviews>
                         <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="pgc-1V-BCe">
-                            <rect key="frame" x="0.0" y="0.0" width="414" height="768"/>
+                            <rect key="frame" x="0.0" y="0.0" width="414" height="812"/>
                             <color key="backgroundColor" systemColor="systemBackgroundColor" cocoaTouchSystemColor="whiteColor"/>
                         </view>
                         <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="0sS-tG-DzA">
-                            <rect key="frame" x="0.0" y="768" width="414" height="50"/>
+                            <rect key="frame" x="0.0" y="812" width="414" height="50"/>
                             <color key="backgroundColor" systemColor="systemBackgroundColor" cocoaTouchSystemColor="whiteColor"/>
                             <constraints>
                                 <constraint firstAttribute="height" constant="50" placeholder="YES" id="Tq2-i3-6qV"/>
@@ -39,7 +39,7 @@
             </subviews>
             <color key="backgroundColor" systemColor="systemBackgroundColor" cocoaTouchSystemColor="whiteColor"/>
             <constraints>
-                <constraint firstItem="0Hi-U6-ohm" firstAttribute="top" secondItem="fnl-2z-Ty3" secondAttribute="top" id="Sny-jC-qtZ"/>
+                <constraint firstItem="0Hi-U6-ohm" firstAttribute="top" secondItem="i5M-Pr-FkT" secondAttribute="top" id="Sny-jC-qtZ"/>
                 <constraint firstItem="fnl-2z-Ty3" firstAttribute="trailing" secondItem="0Hi-U6-ohm" secondAttribute="trailing" id="hbI-xD-9g6"/>
                 <constraint firstItem="fnl-2z-Ty3" firstAttribute="bottom" secondItem="0Hi-U6-ohm" secondAttribute="bottom" id="jyt-Qs-ekO"/>
                 <constraint firstItem="0Hi-U6-ohm" firstAttribute="leading" secondItem="fnl-2z-Ty3" secondAttribute="leading" id="yfB-fN-j1x"/>