NativeScript/tests/app/ui/tabs/tabs-tests-native.ios.ts

import { Tabs } from "@nativescript/core/ui/tabs";
import { Font } from "@nativescript/core/ui/styling/font";

// TODO: Should we add getCount to UIPageViewController???
export function getNativeTabCount(tabView: Tabs): number {
    if (!(<any>tabView).viewControllers) {
        return 0;
    }

    return (<any>tabView).viewControllers.length;
}

// TODO: separate in another function with Tabs implementation - selectNativeTab()
export function selectNativeTab(tabView: Tabs, index: number): void {
    const item = tabView.items[index];
    const controllers = NSMutableArray.alloc<UIViewController>().initWithCapacity(1);

    let itemController = (<any>item).__controller;
    controllers.addObject(itemController);
    let navigationDirection = UIPageViewControllerNavigationDirection.Forward;
    tabView.viewController.setViewControllersDirectionAnimatedCompletion(controllers, navigationDirection, false, null);
    tabView.viewController.delegate.pageViewControllerDidFinishAnimatingPreviousViewControllersTransitionCompleted(tabView.viewController, true, null, true);
}

// TODO: Should we add getNativeSelectedIndex to UIPageViewController???
export function getNativeSelectedIndex(tabView: Tabs): number {
    return tabView.selectedIndex;
}

export function getNativeFont(tabView: Tabs): UIFont {
    const tabBar = <UITabBar>tabView.viewController.tabBar;
    if (tabBar.items.count > 0) {
        const currentAttrs = tabBar.items[0].titleTextAttributesForState(UIControlState.Normal);
        if (currentAttrs) {
            return currentAttrs.objectForKey(NSFontAttributeName);
        }
    }

    return null;
}

export function getOriginalFont(tabView: Tabs): UIFont {
    return (tabView.style.fontInternal || Font.default).getUIFont(UIFont.systemFontOfSize(10));
}