Fixes TabView icons changes. (#4666)

* Fixes TabView icons/title changes.

* Access TabLayput trough parent

* TabView icon change example

apps/app/ui-tests-app/tab-view/main-page.ts

@@ -19,6 +19,7 @@ export function loadExamples() {
     examples.set("tabmore", "tab-view/tab-view-more");
     examples.set("tabViewCss", "tab-view/tab-view-css");
     examples.set("tab-view-icons", "tab-view/tab-view-icon");
+    examples.set("tab-view-icon-change", "tab-view/tab-view-icon-change");
     examples.set("text-transform", "tab-view/text-transform");
     return examples;
 }

apps/app/ui-tests-app/tab-view/tab-view-icon-change.ts

@@ -0,0 +1,17 @@
+import { EventData } from "tns-core-modules/data/observable";
+import { Button } from "tns-core-modules/ui/button";
+import { TabView, SelectedIndexChangedEventData } from "tns-core-modules/ui/tab-view";
+
+export function onSelectedIndexChanged(args: SelectedIndexChangedEventData) {
+    const tabView = args.object as TabView;
+    
+    const newItem = tabView.items[args.newIndex];
+    if (newItem) {
+        newItem.iconSource = "res://icon";
+    }
+
+    const oldItem = tabView.items[args.oldIndex];
+    if (oldItem) {
+        oldItem.iconSource = "res://testlogo";
+    }
+}

apps/app/ui-tests-app/tab-view/tab-view-icon-change.xml

@@ -0,0 +1,16 @@
+ <Page xmlns="http://schemas.nativescript.org/tns.xsd" navigatingTo="onNavigatingTo">
+    <TabView id="tab-view" selectedIndexChanged="onSelectedIndexChanged" iosIconRenderingMode="alwaysOriginal">
+        <TabView.items>
+            <TabViewItem iconSource="res://icon">
+                <TabViewItem.view>
+                    <Label text="first tab"/>
+                </TabViewItem.view>
+            </TabViewItem>
+            <TabViewItem iconSource="res://testlogo"> 
+                <TabViewItem.view>
+                    <Label text="second tab"/>
+                </TabViewItem.view>
+            </TabViewItem>
+        </TabView.items>
+    </TabView>
+</Page>