Selected shipping option in payment summary view + shipping option selection view

ios/chrome/browser/payments/shipping_address_selection_view_controller.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/payments/shipping_address_selection_view_controller.h"
 
 #import "base/ios/weak_nsobject.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 122 matching lines @@
 }
 
 #pragma mark UICollectionViewDelegate
 
 - (void)collectionView:(UICollectionView*)collectionView
     didSelectItemAtIndexPath:(NSIndexPath*)indexPath {
   [super collectionView:collectionView didSelectItemAtIndexPath:indexPath];
 
   CollectionViewModel* model = self.collectionViewModel;
 
-  NSInteger itemType =
-      [self.collectionViewModel itemTypeForIndexPath:indexPath];
-  CollectionViewItem* item =
-      [self.collectionViewModel itemAtIndexPath:indexPath];
+  NSInteger itemType = [model itemTypeForIndexPath:indexPath];
+  if (itemType == ItemTypeShippingAddress) {
+    NSIndexPath* currentlySelectedIndexPath = [self.collectionViewModel
+               indexPathForItem:_selectedItem
+        inSectionWithIdentifier:SectionIdentifierShippingAddress];
+    if (currentlySelectedIndexPath != indexPath) {
+      // Update the cells.
+      CollectionViewItem* item = [model itemAtIndexPath:indexPath];
+      ShippingAddressItem* newlySelectedItem =
+          base::mac::ObjCCastStrict<ShippingAddressItem>(item);
+      newlySelectedItem.accessoryType = MDCCollectionViewCellAccessoryCheckmark;
 
-  if (itemType == ItemTypeShippingAddress) {
-    NSInteger index = [model indexInItemTypeForIndexPath:indexPath];
-    DCHECK(index < (NSInteger)_shippingAddresses.size());
-    self.selectedShippingAddress = _shippingAddresses[index];
+      _selectedItem.accessoryType = MDCCollectionViewCellAccessoryNone;
 
-    ShippingAddressItem* shippingAddressItem =
-        base::mac::ObjCCastStrict<ShippingAddressItem>(item);
-    shippingAddressItem.accessoryType = MDCCollectionViewCellAccessoryCheckmark;
-    _selectedItem.accessoryType = MDCCollectionViewCellAccessoryNone;
-    [self reconfigureCellsForItems:@[ _selectedItem, shippingAddressItem ]
-           inSectionWithIdentifier:SectionIdentifierShippingAddress];
-    _selectedItem = shippingAddressItem;
+      [self reconfigureCellsForItems:@[ _selectedItem, newlySelectedItem ]
+             inSectionWithIdentifier:SectionIdentifierShippingAddress];
 
+      // Update the selected shipping address and its respective item.
+      NSInteger index = [model indexInItemTypeForIndexPath:indexPath];
+      DCHECK(index < (NSInteger)_shippingAddresses.size());
+      self.selectedShippingAddress = _shippingAddresses[index];
+      _selectedItem = newlySelectedItem;
+    }
     [_delegate
         shippingAddressSelectionViewController:self
                        selectedShippingAddress:self.selectedShippingAddress];
   }
   // TODO(crbug.com/602666): Present a shipping address addition UI when
   // itemType == ItemTypeAddShippingAddress.
 }
 
 #pragma mark MDCCollectionViewStylingDelegate
 
 - (CGFloat)collectionView:(UICollectionView*)collectionView
     cellHeightAtIndexPath:(NSIndexPath*)indexPath {
   NSInteger type = [self.collectionViewModel itemTypeForIndexPath:indexPath];
   if (type == ItemTypeAddShippingAddress) {
     return MDCCellDefaultOneLineHeight;
   } else {
     CollectionViewItem* item =
         [self.collectionViewModel itemAtIndexPath:indexPath];
     return [MDCCollectionViewCell
         cr_preferredHeightForWidth:CGRectGetWidth(collectionView.bounds)
                            forItem:item];
   }
 }
 
 @end