fix erorrs

Samples/UIWidgetsSamples_2019_4/Assets/UIWidgetsGallery/demo/cupertino/cupertino_activity_indicator_demo.cs

 
 namespace UIWidgetsGallery.gallery {
     public class CupertinoProgressIndicatorDemo : StatelessWidget {
+        public static string routeName = "/cupertino/progress_indicator";
-                    automaticallyImplyLeading: false,
-                    middle: new Text(
-                        "Activity Indicator"
-                    )
-                ),
+                    previousPageTitle: "Cupertino",
+                    middle: new Text("Activity Indicator")
+           
+                ), 
                 child: new Center(
                     child: new CupertinoActivityIndicator()
                 )

Samples/UIWidgetsSamples_2019_4/Assets/UIWidgetsGallery/demo/cupertino/cupertino_refresh_demo.cs

       
       List<List<string>> randomizedContacts;
 
-      public override void initState() {
+      public override void initState()
+      {
+       
-      void repopulateList() {
+      void repopulateList()
+      {
+        //List<string> nullStr = new List<string>();//{" "};
+        randomizedContacts = new List<List<string>>();
+        
-        for (int index = 0; index < 100; index++ ){
-          contacts[random.Next()].Add(random.Next()%2 == 0 ? true.ToString() : false.ToString());
-          randomizedContacts.Add(contacts[random.Next()]);
+        
+        for (int index = 0; index < 100; index++ )
+        {
+          var id = random.Next(contacts.Count);
+          if (id < contacts.Count)
+          {
+              contacts[id].Add(id %  2 == 0 ? true.ToString() : false.ToString());
+              randomizedContacts.Add(new List<string>());
+              for (int i = 0; i < 4; i++)
+              {
+                randomizedContacts[index].Add(contacts[id][i]);
+              }
+          }
+        _ListItem getListItem(int index)
+        {
+          if (index < randomizedContacts.Count && index > 0 )
+          {
+            return new _ListItem(
+              name: randomizedContacts[index][0],
+              place: randomizedContacts[index][1],
+              date: randomizedContacts[index][2],
+              called: randomizedContacts[index][3] == "true"
+            );
+          }
+          else
+          {
+            return new _ListItem();
+          }
+        }
+
-            
-                  
                   previousPageTitle: "Cupertino"
                   //trailing: CupertinoDemoDocumentationButton(CupertinoRefreshControlDemo.routeName),
                 ),
                   top: false, // Top safe area is consumed by the navigation bar.
                   sliver: new SliverList(
                     del: new SliverChildBuilderDelegate(
-                      (BuildContext context1, int index)=> {
-                        return new _ListItem(
-                          name: randomizedContacts[index][0],
-                          place: randomizedContacts[index][1],
-                          date: randomizedContacts[index][2],
-                          called: randomizedContacts[index][3] == "true"
-                        );
+                      (BuildContext context1, int index)=>
+                      {
+                        return getListItem(index);
                       },
                       childCount: 20
                     )
         string name = null,
         string place = null,
         string date = null,
-        bool? called = null
+        bool called = false
       )
       {
         this.name = name;
       public readonly string name;
       public readonly string place;
       public readonly string date;
-      public readonly bool? called;
+      public readonly bool called;
 
       public override Widget build(BuildContext context) {
         return new Container(
             children: new List<Widget>{
               new Container(
                 width: 38.0f,
-                child: (bool)called
+                child: called
                     ? new Align(
                         alignment: Alignment.topCenter,
                         child: new Icon(
                       )
                     : null
               ),
-            new Expanded(
-              child: new Container(
+              new Expanded(
+                child: new Container(
                   decoration: new  BoxDecoration(
                     border: new Border(
                       bottom: new BorderSide(color: new Color(0xFFBCBBC1), width: 0.0f)
                           mainAxisAlignment: MainAxisAlignment.spaceBetween,
                           children: new List<Widget>{
                             new Text(
-                              name,
+                              name ?? "",
                               maxLines: 1,
                               overflow: TextOverflow.ellipsis,
                               style: new TextStyle(
                             ),
                             new Text(
-                              place,
+                              place ?? "",
                               maxLines: 1,
                               overflow: TextOverflow.ellipsis,
                               style: new TextStyle(
                         )
                       ),
                       new Text(
-                        date,
+                        date ?? "",
                         style: new TextStyle(
                           color: CupertinoColors.inactiveGray.resolveFrom(context),
                           fontSize: 15.0f,

com.unity.uiwidgets/Runtime/cupertino/segmented_control.cs

         Color selectedColor = null,
         Color borderColor = null,
         Color pressedColor = null,
-        EdgeInsetsGeometry Padding = null
+        EdgeInsetsGeometry padding = null
-        { 
-            D.assert(children != null);
+        { D.assert(children != null);
           D.assert(children.Count >= 2);
           D.assert(onValueChanged != null);
           D.assert(
+          this.children = children;
+          this.onValueChanged = onValueChanged;
+          this.groupValue = groupValue;
+          this.unselectedColor = unselectedColor;
+          this.selectedColor = selectedColor;
+          this.borderColor = borderColor;
+          this.pressedColor = pressedColor;
+          this.padding = padding;
+
         }
       public readonly Dictionary<T, Widget> children;
       public readonly T groupValue;
         }
         _selectionControllers.Clear();
         _childTweens.Clear();
-
         foreach ( T key in widget.children.Keys) {
            AnimationController animationController = createAnimationController();
           if (widget.groupValue.Equals(key)) {

com.unity.uiwidgets/Runtime/cupertino/sliding_segmented_control.cs

         {
             D.assert(children != null);
             D.assert(children.Count >= 2);
-            D.assert(padding != null);
             D.assert(onValueChanged != null);
             D.assert(
                 groupValue == null || children.Keys.Contains(groupValue),()=>
         public _RenderSlidingSegmentedControl(
             int? selectedIndex = null,
             Color thumbColor = null,
-            _SlidingSegmentedControlState<T> state = null
+            _SlidingSegmentedControlState<T> state = null 
-            highlightedIndex = selectedIndex;
-            _thumbColor = thumbColor;
-            state.drag.onDown = _onDown;
-            state.drag.onUpdate = _onUpdate;
-            state.drag.onEnd = _onEnd;
-            state.drag.onCancel = _onCancel;
-            state.tap.onTapUp = _onTapUp;
-            state.longPress.onLongPress = ()=> { };
-       }
-        public readonly _SlidingSegmentedControlState<T> state;
-
-  Dictionary<RenderBox, _ChildAnimationManifest> _childAnimations = new Dictionary<RenderBox, _ChildAnimationManifest>{};
+            _highlightedIndex = selectedIndex;
+            _thumbColor = thumbColor;
+            this.state = state;
+            this.state.drag.onDown = _onDown;
+            this.state.drag.onUpdate = _onUpdate;
+            this.state.drag.onEnd = _onEnd;
+            this.state.drag.onCancel = _onCancel;
+            this.state.tap.onTapUp = _onTapUp;
+            this.state.longPress.onLongPress = ()=> { };
+        }
+        public _SlidingSegmentedControlState<T> state;
+        Dictionary<RenderBox, _ChildAnimationManifest> _childAnimations = new Dictionary<RenderBox, _ChildAnimationManifest>{};
 
   
   Rect currentThumbRect;
     base.insert(child, after: after);
     if (_childAnimations == null)
       return;
-
-    D.assert(_childAnimations[child] == null);
+    D.assert(_childAnimations.getOrDefault(child) == null);
     _childAnimations[child] = new _ChildAnimationManifest(separatorOpacity: 1);
   }
 
           transform: MatrixUtils.forceToPoint(center),
           position: center,
           hitTest: (BoxHitTestResult result1, Offset position1)=> {
-            D.assert(position == center);
+            D.assert(position1 == center);
             return child.hitTest(result1, position: center);
           }
         );