diff --git a/example/ios/Flutter/flutter_export_environment.sh b/example/ios/Flutter/flutter_export_environment.sh
new file mode 100644
index 0000000..f27e609
--- /dev/null
+++ b/example/ios/Flutter/flutter_export_environment.sh
@@ -0,0 +1,13 @@
+#!/bin/sh
+# This is a generated file; do not edit or check into version control.
+export "FLUTTER_ROOT=C:\src\flutter"
+export "FLUTTER_APPLICATION_PATH=C:\github_requests\modal_progress_hud\example"
+export "FLUTTER_TARGET=lib\main.dart"
+export "FLUTTER_BUILD_DIR=build"
+export "SYMROOT=${SOURCE_ROOT}/../build\ios"
+export "FLUTTER_BUILD_NAME=1.0.0"
+export "FLUTTER_BUILD_NUMBER=1"
+export "DART_OBFUSCATION=false"
+export "TRACK_WIDGET_CREATION=false"
+export "TREE_SHAKE_ICONS=false"
+export "PACKAGE_CONFIG=.packages"
diff --git a/example/pubspec.lock b/example/pubspec.lock
index 8d79b27..2753873 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -1,48 +1,83 @@
 # Generated by pub
-# See https://www.dartlang.org/tools/pub/glossary#lockfile
+# See https://dart.dev/tools/pub/glossary#lockfile
 packages:
+  _fe_analyzer_shared:
+    dependency: transitive
+    description:
+      name: _fe_analyzer_shared
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "14.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.33.3+2"
+    version: "0.41.2"
+  archive:
+    dependency: transitive
+    description:
+      name: archive
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.13"
   args:
     dependency: transitive
     description:
       name: args
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.1"
+    version: "1.6.0"
   async:
     dependency: transitive
     description:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "2.1.0"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
+    version: "1.2.0"
+  cli_util:
+    dependency: transitive
+    description:
+      name: cli_util
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.3.0"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.11"
+    version: "1.15.0"
   convert:
     dependency: transitive
     description:
@@ -50,20 +85,20 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.1.1"
-  crypto:
+  coverage:
     dependency: transitive
     description:
-      name: crypto
+      name: coverage
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.6"
-  csslib:
+    version: "0.15.2"
+  crypto:
     dependency: transitive
     description:
-      name: csslib
+      name: crypto
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.14.6"
+    version: "2.1.5"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -71,13 +106,20 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.1.2"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
   file:
     dependency: transitive
     description:
       name: file
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "5.0.7"
+    version: "6.0.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -93,13 +135,6 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
-  front_end:
-    dependency: transitive
-    description:
-      name: front_end
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.1.6+5"
   fuchsia_remote_debug_protocol:
     dependency: transitive
     description: flutter
@@ -112,13 +147,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.1.7"
-  html:
-    dependency: transitive
-    description:
-      name: html
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.13.3+3"
   http:
     dependency: transitive
     description:
@@ -140,13 +168,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "3.1.3"
-  intl:
-    dependency: transitive
-    description:
-      name: intl
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.15.7"
   io:
     dependency: transitive
     description:
@@ -160,42 +181,28 @@ packages:
       name: js
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.6.1+1"
-  json_rpc_2:
-    dependency: transitive
-    description:
-      name: json_rpc_2
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.9"
-  kernel:
-    dependency: transitive
-    description:
-      name: kernel
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.3.6+5"
+    version: "0.6.3"
   logging:
     dependency: transitive
     description:
       name: logging
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.11.3+2"
+    version: "1.0.0"
   matcher:
     dependency: transitive
     description:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.3+1"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0"
   mime:
     dependency: transitive
     description:
@@ -209,14 +216,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.1.2"
-  multi_server_socket:
-    dependency: transitive
-    description:
-      name: multi_server_socket
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.0.2"
+    version: "1.0.0"
   node_preamble:
     dependency: transitive
     description:
@@ -230,7 +230,7 @@ packages:
       name: package_config
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.5"
+    version: "1.9.3"
   package_resolver:
     dependency: transitive
     description:
@@ -244,42 +244,35 @@ packages:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.2"
+    version: "1.8.0"
   pedantic:
     dependency: transitive
     description:
       name: pedantic
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.4.0"
+    version: "1.11.0"
   platform:
     dependency: transitive
     description:
       name: platform
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.2.0"
-  plugin:
-    dependency: transitive
-    description:
-      name: plugin
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.2.0+3"
+    version: "3.0.0"
   pool:
     dependency: transitive
     description:
       name: pool
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.6"
+    version: "1.5.0"
   process:
     dependency: transitive
     description:
       name: process
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "3.0.9"
+    version: "4.0.0"
   pub_semver:
     dependency: transitive
     description:
@@ -287,20 +280,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.4.2"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.1"
   shelf:
     dependency: transitive
     description:
       name: shelf
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.7.3+3"
+    version: "0.7.9"
   shelf_packages_handler:
     dependency: transitive
     description:
@@ -321,7 +307,7 @@ packages:
       name: shelf_web_socket
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.2+4"
+    version: "0.2.4+1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -333,98 +319,98 @@ packages:
       name: source_map_stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.5"
+    version: "2.1.0"
   source_maps:
     dependency: transitive
     description:
       name: source_maps
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.10.8"
+    version: "0.10.10"
   source_span:
     dependency: transitive
     description:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.4"
+    version: "1.8.0"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.8"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.1.0"
+  sync_http:
+    dependency: transitive
+    description:
+      name: sync_http
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.2.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0"
   test:
     dependency: "direct dev"
     description:
       name: test
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.3"
+    version: "1.16.5"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.2"
+    version: "0.2.19"
   test_core:
     dependency: transitive
     description:
       name: test_core
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.1+1"
+    version: "0.3.15"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
-  utf:
-    dependency: transitive
-    description:
-      name: utf
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.9.0+5"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
-  vm_service_client:
+    version: "2.1.0"
+  vm_service:
     dependency: transitive
     description:
-      name: vm_service_client
+      name: vm_service
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.6"
+    version: "5.5.0"
   watcher:
     dependency: transitive
     description:
@@ -438,7 +424,21 @@ packages:
       name: web_socket_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.9"
+    version: "1.2.0"
+  webdriver:
+    dependency: transitive
+    description:
+      name: webdriver
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.2"
+  webkit_inspection_protocol:
+    dependency: transitive
+    description:
+      name: webkit_inspection_protocol
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.0"
   yaml:
     dependency: transitive
     description:
@@ -447,4 +447,4 @@ packages:
     source: hosted
     version: "2.1.15"
 sdks:
-  dart: ">=2.1.0 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"
diff --git a/lib/modal_progress_hud.dart b/lib/modal_progress_hud.dart
index da9186d..b2fb9c5 100644
--- a/lib/modal_progress_hud.dart
+++ b/lib/modal_progress_hud.dart
@@ -24,22 +24,22 @@ import 'package:flutter/material.dart';
 ///
 class ModalProgressHUD extends StatelessWidget {
   final bool inAsyncCall;
-  final double opacity;
-  final Color color;
+  final double? opacity;
+  final Color? color;
   final Widget progressIndicator;
-  final Offset offset;
+  final Offset? offset;
   final bool dismissible;
   final Widget child;
 
   ModalProgressHUD({
-    Key key,
-    @required this.inAsyncCall,
+    Key? key,
+    required this.inAsyncCall,
     this.opacity = 0.3,
     this.color = Colors.grey,
     this.progressIndicator = const CircularProgressIndicator(),
     this.offset,
     this.dismissible = false,
-    @required this.child,
+    required this.child,
   })  : assert(child != null),
         assert(inAsyncCall != null),
         super(key: key);
@@ -54,8 +54,8 @@ class ModalProgressHUD extends StatelessWidget {
     else {
       layOutProgressIndicator = Positioned(
         child: progressIndicator,
-        left: offset.dx,
-        top: offset.dy,
+        left: offset!.dx,
+        top: offset!.dy,
       );
     }
 
@@ -64,7 +64,7 @@ class ModalProgressHUD extends StatelessWidget {
         child,
         new Opacity(
           child: new ModalBarrier(dismissible: dismissible, color: color),
-          opacity: opacity,
+          opacity: opacity!,
         ),
         layOutProgressIndicator,
       ],
diff --git a/pubspec.lock b/pubspec.lock
index ea890ff..49a0ce6 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -1,5 +1,5 @@
 # Generated by pub
-# See https://www.dartlang.org/tools/pub/glossary#lockfile
+# See https://dart.dev/tools/pub/glossary#lockfile
 packages:
   async:
     dependency: transitive
@@ -7,28 +7,49 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.5.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "2.1.0"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
+    version: "1.2.0"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.11"
+    version: "1.15.0"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -45,35 +66,21 @@ packages:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.3+1"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.2"
-  pedantic:
-    dependency: transitive
-    description:
-      name: pedantic
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.4.0"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.1"
+    version: "1.8.0"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -85,55 +92,55 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.4"
+    version: "1.8.0"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.8"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.2"
+    version: "0.2.19"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.1.0"
 sdks:
-  dart: ">=2.1.0 <3.0.0"
+  dart: ">=2.12.0 <3.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index e74b5b2..d747127 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,11 +1,11 @@
 name: modal_progress_hud
 description: A modal progress indicator widget (HUD = heads-up display). Wrap around another widget to block access to widget during an async call. Also accepts a custom spinner.
-version: 0.1.3
+version: 1.0.0
 author: Maurice McCabe <mmcc007@gmail.com>
 homepage: https://github.com/mmcc007/modal_progress_hud
 
 environment:
-  sdk: '>=1.20.1 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter:
diff --git a/test/modal_progress_hud_test.dart b/test/modal_progress_hud_test.dart
index 4e21288..083bd8a 100644
--- a/test/modal_progress_hud_test.dart
+++ b/test/modal_progress_hud_test.dart
@@ -5,7 +5,7 @@ import 'package:modal_progress_hud/modal_progress_hud.dart';
 
 void main() {
   group('Modal Progress HUD', () {
-    Widget sut(bool inAsyncCall, Offset offset) {
+    Widget sut(bool inAsyncCall, Offset? offset) {
       return MaterialApp(
         home: new ModalProgressHUD(
           inAsyncCall: inAsyncCall,