NativeScript ActionBar Opacity - ios

Question

I try to change the opacity of the actionbar. For test i try to change the color over native method but this won't work.
I don't understand why, other native functions like UIAlert works fine.
I have no error or anything else only that the actionbar looks like this:
My target is completely transparent because the background has a gradient.
This is my page loaded function:
loaded(args){
let page = <Page>args.object;
page.bindingContext = appViewModel;
if (page.ios) {
var controller = frameModule.topmost().ios.controller;
var navigationBar = controller.navigationBar;
navigationBar.barTintColor = UIColor.blueColor();
}
}
thanks for help
UPDATE
my ts code:
var frameModule = require("ui/frame");
import {topmost} from "ui/frame";
import {Page} from "ui/page";
import {Observable, EventData} from "data/observable";
import {View} from "ui/core/view";
let appViewModel = new Observable({selectedPage: "dashboard"});
export abstract class BasePage {
//implement this function in the inheriting pages to set their specific binding context
abstract mainContentLoaded(args:EventData);
loaded(args){
let page = <Page>args.object;
page.bindingContext = appViewModel;
if (page.ios) {
frameModule.topmost().ios.navBarVisibility = "always";
page.ios.title = "Test Application";
var controller = frameModule.topmost().ios.controller;
var navBar = controller.navigationBar;
navBar.barTintColor = UIColor.redColor();
navBar.navigationBarHidden = false;
navBar.barStyle = UIBarStyle.UIBarStyleBlackTranslucent;
}
}
toggleDrawer(){
let page = <Page>topmost().currentPage;
let drawer = <any>page.getViewById("sidebar");
drawer.toggleDrawerState();
}
navigate(args){
let pageName = args.view.text.toLowerCase();
appViewModel.set("selectedPage", pageName);
topmost().navigate("modules/" + pageName + "/" + pageName);
}
}
my xml:
<page
xmlns="http://schemas.nativescript.org/tns.xsd"
xmlns:drawer="nativescript-telerik-ui/sidedrawer"
xmlns:widgets="shared/widgets"
loaded="loaded">
<page.actionBar>
<action-bar>
<navigation-button icon="res://ic_menu" tap="toggleDrawer" ios:visibility="collapsed" />
<action-bar.actionItems>
<ios>
<action-item icon="res://ic_menu" ios.position="left" tap="toggleDrawer" />
</ios>
</action-bar.actionItems>
</action-bar>
</page.actionBar>
<drawer:rad-side-drawer id="sidebar">
<drawer:rad-side-drawer.mainContent>
</drawer:rad-side-drawer.mainContent>
<drawer:rad-side-drawer.drawerContent>
<widgets:drawer-content />
</drawer:rad-side-drawer.drawerContent>
</drawer:rad-side-drawer>
</page>

Answer 1

The following solution worked out for me (iOS 9.3 with NativeScript 2.0.1)
if (page.ios) {
frameModule.topmost().ios.navBarVisibility = "always";
page.ios.title = "Test Application";
var controller = frameModule.topmost().ios.controller;
var navBar = controller.navigationBar;
navBar.barTintColor = UIColor.redColor();
navBar.navigationBarHidden = false;
navBar.barStyle = UIBarStyle.UIBarStyleBlackTranslucent;
}