add showPlatformDatePicker global method

Author: robert-virkus

lib/src/platform/platform_time_picker.dart

@@ -77,3 +77,98 @@ Future<TimeOfDay?> showPlatformTimePicker({
     );
   }
 }
+
+/// Shows a platform specific date picker with the given [initialDateTime] with a possible range starting with [firstDate] and ending with [lastDate].
+///
+/// On iOS and macOS a CupertinoDatePicker is used. The [builder], [initialEntryMode], [helpText], [useRootNavigator] and [rootSettings] parameters are ignored there.
+/// On other platforms the Material [showTimePicker] method is called with the given parameters.
+Future<DateTime?> showPlatformDatePicker({
+  required BuildContext context,
+  required DateTime initialDate,
+  required DateTime firstDate,
+  required DateTime lastDate,
+  DateTime? currentDate,
+  DatePickerEntryMode initialEntryMode = DatePickerEntryMode.calendar,
+  SelectableDayPredicate? selectableDayPredicate,
+  String? helpText,
+  String? cancelText,
+  String? confirmText,
+  Locale? locale,
+  bool useRootNavigator = true,
+  RouteSettings? routeSettings,
+  TextDirection? textDirection,
+  TransitionBuilder? builder,
+  DatePickerMode initialDatePickerMode = DatePickerMode.day,
+  String? errorFormatText,
+  String? errorInvalidText,
+  String? fieldHintText,
+  String? fieldLabelText,
+}) async {
+  if (Platform.isIOS || Platform.isMacOS) {
+    DateTime? pickedTime;
+    final result = await showCupertinoModalPopup<bool>(
+      context: context,
+      builder: (context) => SizedBox(
+        width: MediaQuery.of(context).size.width,
+        height: MediaQuery.of(context).size.height * 0.4,
+        child: Container(
+          color: CupertinoTheme.of(context).barBackgroundColor,
+          child: Column(
+            children: [
+              Row(
+                mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                children: [
+                  CupertinoButton(
+                      child: (cancelText != null)
+                          ? Text(cancelText)
+                          : Icon(CupertinoIcons.clear_circled),
+                      onPressed: () => Navigator.of(context).pop(false)),
+                  CupertinoButton(
+                      child: (confirmText != null)
+                          ? Text(confirmText)
+                          : Icon(CupertinoIcons.check_mark_circled),
+                      onPressed: () => Navigator.of(context).pop(true)),
+                ],
+              ),
+              Expanded(
+                child: CupertinoDatePicker(
+                  mode: CupertinoDatePickerMode.date,
+                  onDateTimeChanged: (value) => pickedTime = value,
+                  use24hFormat: MediaQuery.of(context).alwaysUse24HourFormat,
+                  initialDateTime: initialDate,
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+    if (result == true && pickedTime != null) {
+      return pickedTime;
+    }
+    return null;
+  } else {
+    return showDatePicker(
+      context: context,
+      initialDate: initialDate,
+      firstDate: firstDate,
+      lastDate: lastDate,
+      currentDate: currentDate,
+      initialEntryMode: initialEntryMode,
+      selectableDayPredicate: selectableDayPredicate,
+      helpText: helpText,
+      cancelText: cancelText,
+      confirmText: confirmText,
+      locale: locale,
+      useRootNavigator: useRootNavigator,
+      routeSettings: routeSettings,
+      textDirection: textDirection,
+      builder: builder,
+      initialDatePickerMode: initialDatePickerMode,
+      errorFormatText: errorFormatText,
+      errorInvalidText: errorInvalidText,
+      fieldHintText: fieldHintText,
+      fieldLabelText: fieldLabelText,
+    );
+  }
+}