diff --git a/.idea/libraries/Dart_Packages.xml b/.idea/libraries/Dart_Packages.xml
index d32b503..ba13c59 100644
--- a/.idea/libraries/Dart_Packages.xml
+++ b/.idea/libraries/Dart_Packages.xml
@@ -5,166 +5,174 @@
         <entry key="async">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/async-2.1.0/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/async-2.5.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
         <entry key="boolean_selector">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/boolean_selector-1.0.4/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/boolean_selector-2.1.0-nullsafety.1/lib" />
+            </list>
+          </value>
+        </entry>
+        <entry key="characters">
+          <value>
+            <list>
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/characters-1.1.0-nullsafety.3/lib" />
             </list>
           </value>
         </entry>
         <entry key="charcode">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/charcode-1.1.2/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/charcode-1.2.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
-        <entry key="collection">
+        <entry key="clock">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/collection-1.14.11/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/clock-1.1.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
-        <entry key="flutter">
+        <entry key="collection">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/packages/flutter/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/collection-1.15.0-nullsafety.3/lib" />
             </list>
           </value>
         </entry>
-        <entry key="flutter_test">
+        <entry key="fake_async">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/packages/flutter_test/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/fake_async-1.2.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
-        <entry key="matcher">
+        <entry key="flutter">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/matcher-0.12.5/lib" />
+              <option value="$USER_HOME$/flutter/packages/flutter/lib" />
             </list>
           </value>
         </entry>
-        <entry key="meta">
+        <entry key="flutter_test">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/meta-1.1.6/lib" />
+              <option value="$USER_HOME$/flutter/packages/flutter_test/lib" />
             </list>
           </value>
         </entry>
-        <entry key="path">
+        <entry key="matcher">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/path-1.6.2/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/matcher-0.12.10-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
-        <entry key="pedantic">
+        <entry key="meta">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/pedantic-1.5.0/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/meta-1.3.0-nullsafety.4/lib" />
             </list>
           </value>
         </entry>
-        <entry key="quiver">
+        <entry key="path">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/quiver-2.0.2/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/path-1.8.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
         <entry key="sky_engine">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/bin/cache/pkg/sky_engine/lib" />
+              <option value="$USER_HOME$/flutter/bin/cache/pkg/sky_engine/lib" />
             </list>
           </value>
         </entry>
         <entry key="source_span">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/source_span-1.5.5/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/source_span-1.8.0-nullsafety.2/lib" />
             </list>
           </value>
         </entry>
         <entry key="stack_trace">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/stack_trace-1.9.3/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/stack_trace-1.10.0-nullsafety.2/lib" />
             </list>
           </value>
         </entry>
         <entry key="stream_channel">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/stream_channel-2.0.0/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/stream_channel-2.1.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
         <entry key="string_scanner">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/string_scanner-1.0.4/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/string_scanner-1.1.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
         <entry key="term_glyph">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/term_glyph-1.1.0/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/term_glyph-1.2.0-nullsafety.1/lib" />
             </list>
           </value>
         </entry>
         <entry key="test_api">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/test_api-0.2.4/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/test_api-0.2.19-nullsafety.2/lib" />
             </list>
           </value>
         </entry>
         <entry key="typed_data">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/typed_data-1.1.6/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/typed_data-1.3.0-nullsafety.3/lib" />
             </list>
           </value>
         </entry>
         <entry key="vector_math">
           <value>
             <list>
-              <option value="$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/vector_math-2.0.8/lib" />
+              <option value="$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/vector_math-2.1.0-nullsafety.3/lib" />
             </list>
           </value>
         </entry>
       </option>
     </properties>
     <CLASSES>
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/async-2.1.0/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/boolean_selector-1.0.4/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/charcode-1.1.2/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/collection-1.14.11/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/matcher-0.12.5/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/meta-1.1.6/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/path-1.6.2/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/pedantic-1.5.0/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/quiver-2.0.2/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/source_span-1.5.5/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/stack_trace-1.9.3/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/stream_channel-2.0.0/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/string_scanner-1.0.4/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/term_glyph-1.1.0/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/test_api-0.2.4/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/typed_data-1.1.6/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/.pub-cache/hosted/pub.flutter-io.cn/vector_math-2.0.8/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/bin/cache/pkg/sky_engine/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/packages/flutter/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter/packages/flutter_test/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/async-2.5.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/boolean_selector-2.1.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/characters-1.1.0-nullsafety.3/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/charcode-1.2.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/clock-1.1.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/collection-1.15.0-nullsafety.3/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/fake_async-1.2.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/matcher-0.12.10-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/meta-1.3.0-nullsafety.4/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/path-1.8.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/source_span-1.8.0-nullsafety.2/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/stack_trace-1.10.0-nullsafety.2/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/stream_channel-2.1.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/string_scanner-1.1.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/term_glyph-1.2.0-nullsafety.1/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/test_api-0.2.19-nullsafety.2/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/typed_data-1.3.0-nullsafety.3/lib" />
+      <root url="file://$USER_HOME$/.pub-cache/hosted/pub.dartlang.org/vector_math-2.1.0-nullsafety.3/lib" />
+      <root url="file://$USER_HOME$/flutter/bin/cache/pkg/sky_engine/lib" />
+      <root url="file://$USER_HOME$/flutter/packages/flutter/lib" />
+      <root url="file://$USER_HOME$/flutter/packages/flutter_test/lib" />
     </CLASSES>
     <JAVADOC />
     <SOURCES />
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 1488020..134d29d 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -7,10 +7,10 @@
   </component>
   <component name="ChangeListManager">
     <list default="true" id="eac6f9fd-8689-46e5-8de2-a90ff16deeed" name="Default" comment="">
+      <change beforePath="$PROJECT_DIR$/.idea/libraries/Dart_Packages.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/libraries/Dart_Packages.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/CHANGELOG.md" beforeDir="false" afterPath="$PROJECT_DIR$/CHANGELOG.md" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/README.md" beforeDir="false" afterPath="$PROJECT_DIR$/README.md" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/pubspec.yaml" beforeDir="false" afterPath="$PROJECT_DIR$/pubspec.yaml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/flutter_cupertino_data_picker.iml" beforeDir="false" afterPath="$PROJECT_DIR$/flutter_cupertino_data_picker.iml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/pubspec.lock" beforeDir="false" afterPath="$PROJECT_DIR$/pubspec.lock" afterDir="false" />
     </list>
     <ignored path="$PROJECT_DIR$/.dart_tool/" />
     <ignored path="$PROJECT_DIR$/.idea/" />
@@ -24,44 +24,14 @@
   </component>
   <component name="FileEditorManager">
     <leaf SIDE_TABS_SIZE_LIMIT_KEY="300">
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/pubspec.yaml">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="242">
-              <caret line="11" column="16" selection-start-line="11" selection-start-column="16" selection-end-line="11" selection-end-column="16" />
-            </state>
-          </provider>
-        </entry>
-      </file>
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/README.md">
-          <provider selected="true" editor-type-id="split-provider[text-editor;MarkdownPreviewEditor]">
-            <state split_layout="SPLIT">
-              <first_editor relative-caret-position="704">
-                <caret line="32" column="15" selection-start-line="32" selection-start-column="15" selection-end-line="32" selection-end-column="15" />
-              </first_editor>
-              <second_editor>
-                <markdownNavigatorState />
-              </second_editor>
-            </state>
-          </provider>
-        </entry>
-      </file>
       <file pinned="false" current-in-tab="true">
-        <entry file="file://$PROJECT_DIR$/example/example.dart">
-          <provider selected="true" editor-type-id="text-editor" />
-        </entry>
-      </file>
-      <file pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/CHANGELOG.md">
-          <provider selected="true" editor-type-id="split-provider[text-editor;MarkdownPreviewEditor]">
-            <state split_layout="SPLIT">
-              <first_editor relative-caret-position="88">
-                <caret line="4" column="22" selection-start-line="4" selection-start-column="22" selection-end-line="4" selection-end-column="22" />
-              </first_editor>
-              <second_editor>
-                <markdownNavigatorState />
-              </second_editor>
+        <entry file="file://$PROJECT_DIR$/lib/flutter_cupertino_data_picker.dart">
+          <provider selected="true" editor-type-id="text-editor">
+            <state relative-caret-position="577">
+              <caret line="54" column="19" selection-start-line="54" selection-start-column="19" selection-end-line="54" selection-end-column="19" />
+              <folding>
+                <element signature="e#74#114#0" expanded="true" />
+              </folding>
             </state>
           </provider>
         </entry>
@@ -99,7 +69,7 @@
       </list>
     </option>
   </component>
-  <component name="ProjectFrameBounds" extendedState="6">
+  <component name="ProjectFrameBounds" extendedState="6" fullScreen="true">
     <option name="y" value="23" />
     <option name="width" value="1680" />
     <option name="height" value="948" />
@@ -110,36 +80,28 @@
       <foldersAlwaysOnTop value="true" />
     </navigator>
     <panes>
+      <pane id="Scope" />
       <pane id="ProjectPane">
         <subPane>
           <expand>
             <path>
-              <item name="flutter_cupertino_data_picker" type="b2602c69:ProjectViewProjectNode" />
-              <item name="flutter_cupertino_data_picker" type="462c0819:PsiDirectoryNode" />
+              <item name="picker" type="b2602c69:ProjectViewProjectNode" />
+              <item name="picker" type="462c0819:PsiDirectoryNode" />
             </path>
             <path>
-              <item name="flutter_cupertino_data_picker" type="b2602c69:ProjectViewProjectNode" />
-              <item name="flutter_cupertino_data_picker" type="462c0819:PsiDirectoryNode" />
+              <item name="picker" type="b2602c69:ProjectViewProjectNode" />
+              <item name="picker" type="462c0819:PsiDirectoryNode" />
               <item name="lib" type="462c0819:PsiDirectoryNode" />
             </path>
-            <path>
-              <item name="flutter_cupertino_data_picker" type="b2602c69:ProjectViewProjectNode" />
-              <item name="flutter_cupertino_data_picker" type="462c0819:PsiDirectoryNode" />
-              <item name="test" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="flutter_cupertino_data_picker" type="b2602c69:ProjectViewProjectNode" />
-              <item name="External Libraries" type="cb654da1:ExternalLibrariesNode" />
-            </path>
           </expand>
           <select />
         </subPane>
       </pane>
       <pane id="PackagesPane" />
-      <pane id="Scope" />
     </panes>
   </component>
   <component name="PropertiesComponent">
+    <property name="SHARE_PROJECT_CONFIGURATION_FILES" value="true" />
     <property name="dart.analysis.tool.window.force.activate" value="false" />
     <property name="last_opened_file_path" value="$PROJECT_DIR$" />
     <property name="settings.editor.selected.configurable" value="flutter.settings" />
@@ -163,15 +125,6 @@
     </option>
   </component>
   <component name="RunManager">
-    <configuration name="&lt;template&gt;" type="Applet" default="true" selected="false">
-      <option name="MAIN_CLASS_NAME" />
-      <option name="HTML_FILE_NAME" />
-      <option name="HTML_USED" value="false" />
-      <option name="WIDTH" value="400" />
-      <option name="HEIGHT" value="300" />
-      <option name="POLICY_FILE" value="$APPLICATION_HOME_DIR$/bin/appletviewer.policy" />
-      <option name="VM_PARAMETERS" />
-    </configuration>
     <configuration name="&lt;template&gt;" type="JUnit" default="true" selected="false">
       <option name="MAIN_CLASS_NAME" />
       <option name="VM_PARAMETERS" value="-ea" />
@@ -181,6 +134,12 @@
     <configuration name="&lt;template&gt;" type="#org.jetbrains.idea.devkit.run.PluginConfigurationType" default="true" selected="false">
       <option name="VM_PARAMETERS" value="-Xmx512m -Xms256m -XX:MaxPermSize=250m -ea" />
     </configuration>
+    <configuration default="true" type="Applet">
+      <option name="POLICY_FILE" value="$APPLICATION_HOME_DIR$/bin/appletviewer.policy" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
     <configuration default="true" type="Application" factoryName="Application">
       <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$" />
       <method v="2">
@@ -208,12 +167,21 @@
       <option name="presentableId" value="Default" />
       <updated>1536900584939</updated>
     </task>
+    <task id="LOCAL-00001" summary="added data theme">
+      <created>1604072162084</created>
+      <option name="number" value="00001" />
+      <option name="presentableId" value="LOCAL-00001" />
+      <option name="project" value="LOCAL" />
+      <updated>1604072162084</updated>
+    </task>
+    <option name="localTasksCounter" value="2" />
     <servers />
   </component>
   <component name="ToolWindowManager">
-    <frame x="0" y="23" width="1680" height="947" extended-state="6" />
+    <frame x="0" y="0" width="3200" height="1800" extended-state="6" />
+    <editor active="true" />
     <layout>
-      <window_info active="true" content_ui="combo" id="Project" order="0" visible="true" weight="0.2832723" />
+      <window_info active="true" content_ui="combo" id="Project" order="0" visible="true" weight="0.2849905" />
       <window_info id="Structure" order="1" side_tool="true" weight="0.25" />
       <window_info id="Favorites" order="2" side_tool="true" />
       <window_info id="Image Layers" order="3" />
@@ -231,7 +199,7 @@
       <window_info anchor="bottom" id="Terminal" order="8" weight="0.32932693" />
       <window_info anchor="bottom" id="Event Log" order="9" side_tool="true" weight="0.32932693" />
       <window_info anchor="bottom" id="Version Control" order="10" />
-      <window_info active="true" anchor="bottom" id="Messages" order="11" visible="true" weight="0.328125" />
+      <window_info active="true" anchor="bottom" id="Messages" order="11" sideWeight="0.49968335" visible="true" weight="0.32774568" />
       <window_info anchor="bottom" id="OkHttp Profiler" order="12" side_tool="true" />
       <window_info anchor="bottom" id="Flutter Performance" order="13" side_tool="true" />
       <window_info anchor="right" id="Commander" order="0" weight="0.4" />
@@ -244,6 +212,10 @@
       <window_info anchor="right" id="Palette&#9;" order="7" />
     </layout>
   </component>
+  <component name="VcsManagerConfiguration">
+    <MESSAGE value="added data theme" />
+    <option name="LAST_COMMIT_MESSAGE" value="added data theme" />
+  </component>
   <component name="editorHistoryManager">
     <entry file="file://$PROJECT_DIR$/screenshots/demo.png">
       <provider selected="true" editor-type-id="images" />
@@ -255,17 +227,11 @@
         </state>
       </provider>
     </entry>
-    <entry file="file://$PROJECT_DIR$/../../../flutter/packages/flutter/lib/src/cupertino/picker.dart">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="1017">
-          <caret line="53" column="30" lean-forward="true" selection-start-line="53" selection-start-column="30" selection-end-line="53" selection-end-column="30" />
-        </state>
-      </provider>
-    </entry>
+    <entry file="file://$PROJECT_DIR$/../../../flutter/packages/flutter/lib/src/cupertino/picker.dart" />
     <entry file="file://$PROJECT_DIR$/lib/flutter_cupertino_data_picker.dart">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="2200">
-          <caret line="104" column="21" selection-start-line="104" selection-start-column="21" selection-end-line="104" selection-end-column="21" />
+        <state relative-caret-position="577">
+          <caret line="54" column="19" selection-start-line="54" selection-start-column="19" selection-end-line="54" selection-end-column="19" />
           <folding>
             <element signature="e#74#114#0" expanded="true" />
           </folding>
@@ -280,16 +246,6 @@
       </provider>
     </entry>
     <entry file="file://$PROJECT_DIR$/CHANGELOG.md">
-      <provider selected="true" editor-type-id="split-provider[text-editor;MarkdownPreviewEditor]">
-        <state split_layout="SPLIT">
-          <first_editor relative-caret-position="88">
-            <caret line="4" column="22" selection-start-line="4" selection-start-column="22" selection-end-line="4" selection-end-column="22" />
-          </first_editor>
-          <second_editor>
-            <markdownNavigatorState />
-          </second_editor>
-        </state>
-      </provider>
       <provider editor-type-id="text-editor">
         <state relative-caret-position="198">
           <caret line="9" lean-forward="true" selection-start-line="9" selection-end-line="9" />
@@ -307,16 +263,6 @@
       </provider>
     </entry>
     <entry file="file://$PROJECT_DIR$/README.md">
-      <provider selected="true" editor-type-id="split-provider[text-editor;MarkdownPreviewEditor]">
-        <state split_layout="SPLIT">
-          <first_editor relative-caret-position="704">
-            <caret line="32" column="15" selection-start-line="32" selection-start-column="15" selection-end-line="32" selection-end-column="15" />
-          </first_editor>
-          <second_editor>
-            <markdownNavigatorState />
-          </second_editor>
-        </state>
-      </provider>
       <provider editor-type-id="text-editor">
         <state relative-caret-position="220">
           <caret line="10" column="8" lean-forward="true" selection-start-line="10" selection-start-column="8" selection-end-line="10" selection-end-column="8" />
diff --git a/flutter_cupertino_data_picker.iml b/flutter_cupertino_data_picker.iml
index 8d48a06..d9bd5ad 100644
--- a/flutter_cupertino_data_picker.iml
+++ b/flutter_cupertino_data_picker.iml
@@ -12,8 +12,8 @@
     </content>
     <orderEntry type="jdk" jdkName="Android API 25 Platform" jdkType="Android SDK" />
     <orderEntry type="sourceFolder" forTests="false" />
-    <orderEntry type="library" name="Dart Packages" level="project" />
     <orderEntry type="library" name="Dart SDK" level="project" />
     <orderEntry type="library" name="Flutter Plugins" level="project" />
+    <orderEntry type="library" name="Dart Packages" level="project" />
   </component>
 </module>
\ No newline at end of file
diff --git a/lib/flutter_cupertino_data_picker.dart b/lib/flutter_cupertino_data_picker.dart
index 57dbd3f..f62a9dc 100644
--- a/lib/flutter_cupertino_data_picker.dart
+++ b/lib/flutter_cupertino_data_picker.dart
@@ -21,9 +21,11 @@ class DataPicker {
     int selectedIndex: 0,
     DateChangedCallback onChanged,
     DateChangedCallback onConfirm,
+    prefix: '',
     suffix: '',
     title: '',
     locale: 'zh',
+    dataStyle: const TextStyle(color: Color(0xFF000046), fontSize: _kDatePickerFontSize),
   }) {
     Navigator.push(
         context,
@@ -34,11 +36,12 @@ class DataPicker {
           onChanged: onChanged,
           onConfirm: onConfirm,
           locale: locale,
+          prefix: prefix,
           suffix: suffix,
           title: title,
-          theme: Theme.of(context, shadowThemeOnly: true),
-          barrierLabel:
-              MaterialLocalizations.of(context).modalBarrierDismissLabel,
+          theme: Theme.of(context),
+          dataStyle: dataStyle,
+          barrierLabel: MaterialLocalizations.of(context).modalBarrierDismissLabel,
         ));
   }
 }
@@ -53,8 +56,10 @@ class _DatePickerRoute<T> extends PopupRoute<T> {
     this.theme,
     this.barrierLabel,
     this.locale,
+    this.prefix,
     this.suffix,
     this.title,
+    this.dataStyle,
     RouteSettings settings,
   }) : super(settings: settings);
 
@@ -65,8 +70,10 @@ class _DatePickerRoute<T> extends PopupRoute<T> {
   final DateChangedCallback onConfirm;
   final ThemeData theme;
   final String locale;
+  final String prefix;
   final String suffix;
   final String title;
+  final TextStyle dataStyle;
 
   @override
   Duration get transitionDuration => const Duration(milliseconds: 200);
@@ -85,14 +92,12 @@ class _DatePickerRoute<T> extends PopupRoute<T> {
   @override
   AnimationController createAnimationController() {
     assert(_animationController == null);
-    _animationController =
-        BottomSheet.createAnimationController(navigator.overlay);
+    _animationController = BottomSheet.createAnimationController(navigator.overlay);
     return _animationController;
   }
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation,
-      Animation<double> secondaryAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     Widget bottomSheet = new MediaQuery.removePadding(
       context: context,
       removeTop: true,
@@ -101,8 +106,10 @@ class _DatePickerRoute<T> extends PopupRoute<T> {
         datas: datas,
         onChanged: onChanged,
         locale: locale,
+        prefix: prefix,
         suffix: suffix,
         title: title,
+        dataStyle: dataStyle,
         route: this,
       ),
     );
@@ -115,14 +122,15 @@ class _DatePickerRoute<T> extends PopupRoute<T> {
 
 class _DataPickerComponent extends StatefulWidget {
   _DataPickerComponent({
-    Key key,
     @required this.route,
     this.initialData: 0,
     this.datas,
     this.onChanged,
     this.locale,
+    this.prefix,
     this.suffix,
     this.title,
+    this.dataStyle,
   });
 
   final DateChangedCallback onChanged;
@@ -132,9 +140,12 @@ class _DataPickerComponent extends StatefulWidget {
   final _DatePickerRoute route;
 
   final String locale;
+  final String prefix;
   final String suffix;
   final String title;
 
+  final TextStyle dataStyle;
+
   @override
   State<StatefulWidget> createState() => _DatePickerState(this.initialData);
 }
@@ -148,8 +159,7 @@ class _DatePickerState extends State<_DataPickerComponent> {
     if (this._initialIndex < 0) {
       this._initialIndex = 0;
     }
-    dataScrollCtrl =
-        new FixedExtentScrollController(initialItem: _selectedColorIndex);
+    dataScrollCtrl = new FixedExtentScrollController(initialItem: _selectedColorIndex);
   }
 
   @override
@@ -160,8 +170,7 @@ class _DatePickerState extends State<_DataPickerComponent> {
         builder: (BuildContext context, Widget child) {
           return new ClipRect(
             child: new CustomSingleChildLayout(
-              delegate: new _BottomPickerLayout(widget.route.animation.value,
-                  showTitleActions: widget.route.showTitleActions),
+              delegate: new _BottomPickerLayout(widget.route.animation.value, showTitleActions: widget.route.showTitleActions),
               child: new GestureDetector(
                 child: Material(
                   color: Colors.transparent,
@@ -202,7 +211,7 @@ class _DatePickerState extends State<_DataPickerComponent> {
     return itemView;
   }
 
-  Widget _renderDataPickerComponent(String suffixAppend) {
+  Widget _renderDataPickerComponent(String prefixAppend, String suffixAppend, TextStyle dataStyle) {
     return new Expanded(
       flex: 1,
       child: Container(
@@ -224,10 +233,8 @@ class _DatePickerState extends State<_DataPickerComponent> {
                   children: <Widget>[
                     new Expanded(
                         child: Text(
-                      '${widget.datas[index]}$suffixAppend',
-                      style: TextStyle(
-                          color: Color(0xFF000046),
-                          fontSize: _kDatePickerFontSize),
+                      '$prefixAppend${widget.datas[index]}$suffixAppend',
+                      style: dataStyle,
                       textAlign: TextAlign.center,
                       softWrap: false,
                       overflow: TextOverflow.fade,
@@ -241,7 +248,7 @@ class _DatePickerState extends State<_DataPickerComponent> {
   }
 
   Widget _renderItemView() {
-    return _renderDataPickerComponent(widget.suffix);
+    return _renderDataPickerComponent(widget.prefix, widget.suffix, widget.dataStyle);
   }
 
   // Title View
@@ -257,7 +264,7 @@ class _DatePickerState extends State<_DataPickerComponent> {
         children: <Widget>[
           Container(
             height: _kDatePickerTitleHeight,
-            child: FlatButton(
+            child: TextButton(
               child: Text(
                 '$cancel',
                 style: TextStyle(
@@ -281,7 +288,7 @@ class _DatePickerState extends State<_DataPickerComponent> {
           ),
           Container(
             height: _kDatePickerTitleHeight,
-            child: FlatButton(
+            child: TextButton(
               child: Text(
                 '$done',
                 style: TextStyle(
@@ -361,11 +368,7 @@ class _BottomPickerLayout extends SingleChildLayoutDelegate {
       maxHeight += _kDatePickerTitleHeight;
     }
 
-    return new BoxConstraints(
-        minWidth: constraints.maxWidth,
-        maxWidth: constraints.maxWidth,
-        minHeight: 0.0,
-        maxHeight: maxHeight);
+    return new BoxConstraints(minWidth: constraints.maxWidth, maxWidth: constraints.maxWidth, minHeight: 0.0, maxHeight: maxHeight);
   }
 
   @override
diff --git a/pubspec.lock b/pubspec.lock
index 10f7aaa..65991e8 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -1,34 +1,55 @@
 # Generated by pub
-# See https://www.dartlang.org/tools/pub/glossary#lockfile
+# See https://dart.dev/tools/pub/glossary#lockfile
 packages:
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0"
+    version: "2.5.0-nullsafety.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "2.1.0-nullsafety.1"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0-nullsafety.3"
   charcode:
     dependency: transitive
     description:
       name: charcode
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0-nullsafety.1"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.2"
+    version: "1.1.0-nullsafety.1"
   collection:
     dependency: transitive
     description:
       name: collection
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.14.11"
+    version: "1.15.0-nullsafety.3"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0-nullsafety.1"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -43,37 +64,23 @@ packages:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.5"
+    version: "0.12.10-nullsafety.1"
   meta:
     dependency: transitive
     description:
       name: meta
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0-nullsafety.4"
   path:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.6.2"
-  pedantic:
-    dependency: transitive
-    description:
-      name: pedantic
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.5.0"
-  quiver:
-    dependency: transitive
-    description:
-      name: quiver
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.2"
+    version: "1.8.0-nullsafety.1"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -83,57 +90,57 @@ packages:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.5.5"
+    version: "1.8.0-nullsafety.2"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "1.10.0-nullsafety.2"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0-nullsafety.1"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.1.0-nullsafety.1"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "1.2.0-nullsafety.1"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.4"
+    version: "0.2.19-nullsafety.2"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.6"
+    version: "1.3.0-nullsafety.3"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
-      url: "https://pub.flutter-io.cn"
+      url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.8"
+    version: "2.1.0-nullsafety.3"
 sdks:
-  dart: ">=2.2.0 <3.0.0"
+  dart: ">=2.10.0-110 <=2.11.0-213.1.beta"