如何在nativescript angular中动态显示默认启动画面

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/colorPrimaryDark" />
    <item>
        <bitmap
            android:src="@drawable/your_image"
            android:gravity="center" />
    </item>
</layer-list>

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="LaunchScreenTheme" parent="AppTheme">
        <item name="android:windowBackground">@drawable/launch_screen</item>
    </style>
</resources>

import { device } from "tns-core-modules/platform";
import { isIOS } from "tns-core-modules/platform";
import { isAndroid } from "tns-core-modules/platform";
import { AndroidActivityBackPressedEventData } from "tns-core-modules/application";

@Component({
    selector: "ns-app",
    templateUrl: "app.component.html",
})

export class AppComponent {
    private androidBackPressedSubscription;

    constructor(
        private zone: NgZone,
        private page: Page,
        private routerExtensions: RouterExtensions
    ) {
        this.page.on("loaded", () => {
            if (isIOS) {
                this.showDefaultLaunchScreen();
            } else if (isAndroid) {
                this.overrideAndroidBackButton();
                this.showDefaultLaunchScreen();
                this.hideDefaultLaunchScreen();
            }
        });
    }

    private showDefaultLaunchScreen() {
        const _launchScreenTimeout = isIOS ? 1000 : 3000;
        const _launchScreenContainer = this.page.getViewById("launch-screen-container");

        if (_launchScreenContainer) {
            _launchScreenContainer.animate({
                opacity: 0,
                duration: _launchScreenTimeout,
                curve: "easeInOut"
            }).then(() => {
                _launchScreenContainer.visibility = "collapse";
            });
        }
    }

    private hideDefaultLaunchScreen() {
        const _launchScreenTimeout = isIOS ? 1000 : 3000;
        const _launchScreenContainer = this.page.getViewById("launch-screen-container");

        setTimeout(() => {
            if (_launchScreenContainer) {
                _launchScreenContainer.visibility = "visible";
                _launchScreenContainer.animate({
                    opacity: 1,
                    duration: _launchScreenTimeout,
                    curve: "easeInOut"
                }).then(() => {
                    // Do something after the launch screen is shown
                });
            }
        }, _launchScreenTimeout);
    }
}

<StackLayout id="launch-screen-container">
    <!-- Place your launch screen content here -->
    <Label text="Loading..." horizontalAlignment="center"></Label>
</StackLayout>