Fix CupertinoAlertDialog TextStyle (#64468)

packages/flutter/lib/src/cupertino/dialog.dart

@@ -18,22 +18,28 @@ import 'scrollbar.dart';
 
 // TODO(abarth): These constants probably belong somewhere more general.
 
+// Used XD to flutter plugin(https://github.com/AdobeXD/xd-to-flutter-plugin/)
+// to derive values of TextStyle(height and letterSpacing) from
+// Adobe XD template for iOS 13, which can be found in
+// Apple Design Resources(https://developer.apple.com/design/resources/).
+// However the values are not exactly the same as native, so eyeballing is needed.
 const TextStyle _kCupertinoDialogTitleStyle = TextStyle(
   fontFamily: '.SF UI Display',
   inherit: false,
-  fontSize: 18.0,
+  fontSize: 17.0,
   fontWeight: FontWeight.w600,
-  letterSpacing: 0.48,
+  height: 1.3,
+  letterSpacing: -0.5,
   textBaseline: TextBaseline.alphabetic,
 );
 
 const TextStyle _kCupertinoDialogContentStyle = TextStyle(
   fontFamily: '.SF UI Text',
   inherit: false,
-  fontSize: 13.4,
+  fontSize: 13.0,
   fontWeight: FontWeight.w400,
-  height: 1.036,
-  letterSpacing: -0.25,
+  height: 1.35,
+  letterSpacing: -0.2,
   textBaseline: TextBaseline.alphabetic,
 );
 

packages/flutter/test/cupertino/dialog_test.dart

@@ -320,7 +320,7 @@ void main() {
     // Visually the "Cancel" button and "OK" button are the same height when using the
     // regular font. However, when using the test font, "Cancel" becomes 2 lines which
     // is why the height we're verifying for "Cancel" is larger than "OK".
-    expect(tester.getSize(find.text('The Title')), equals(const Size(270.0, 162.0)));
+    expect(tester.getSize(find.text('The Title')), equals(const Size(270.0, 132.0)));
     expect(tester.getTopLeft(find.text('The Title')), equals(const Offset(265.0, 80.0 + 24.0)));
     expect(tester.getSize(find.widgetWithText(CupertinoDialogAction, 'Cancel')), equals(const Size(310.0, 148.0)));
     expect(tester.getSize(find.widgetWithText(CupertinoDialogAction, 'OK')), equals(const Size(310.0, 98.0)));
@@ -1147,6 +1147,36 @@ void main() {
     // once animation settles the dialog is padded by the new viewInsets
     expect(tester.getRect(find.byType(Placeholder)), placeholderRectWithoutInsets.translate(10, 10));
   });
+
+  testWidgets('Default cupertino dialog golden', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      createAppWithButtonThatLaunchesDialog(
+        dialogBuilder: (BuildContext context) {
+          return MediaQuery(
+            data: MediaQuery.of(context).copyWith(textScaleFactor: 3.0),
+            child: const RepaintBoundary(
+              child: CupertinoAlertDialog(
+                title: Text('Title'),
+                content: Text('text'),
+                actions: <Widget>[
+                  CupertinoDialogAction(child: Text('No')),
+                  CupertinoDialogAction(child: Text('OK')),
+                ],
+              ),
+            ),
+          );
+        }
+      ),
+    );
+
+    await tester.tap(find.text('Go'));
+    await tester.pumpAndSettle();
+
+    await expectLater(
+      find.byType(CupertinoAlertDialog),
+      matchesGoldenFile('dialog_test.cupertino.default.png'),
+    );
+  });
 }
 
 RenderBox findActionButtonRenderBoxByTitle(WidgetTester tester, String title) {