Application

The Application class provides abstraction over the platform-specific application implementations. It lets you manage things such as handling lifecycle events of your application (cross-platform and/or native), sending Broadcasts on Android or adding a Notification observer on IOS.

Import

JavaScript
TypeScript

import { Application } from '@nativescript/core'

import { Application } from '@nativescript/core'

Android

For android, you can access the main activity for the application, currently active activity, a method to register a broadcast receiver and other Android-specific properties and methods, as you will see below.

Android Properties

android

The property gives you the Nativescript wrapper, the AndroidApplication object, around the native android native application instance.

JavaScript
TypeScript

const androidApp = Application.android

const androidApp: AndroidApplication = Application.android

nativeApp

This is a native application reference. Basically, it is the android.app.Application instance keeping track of the global application state. From this object you can get methods such as getFilesDir(), onLowMemory(),etc.

Type:

android.app.Application

JavaScript
TypeScript

const nativeApp = androidApp.nativeApp

const nativeApp: android.app.Application = androidApp.nativeApp

foregroundActivity

The reference to the currently active (loaded) android Activity. This property is automatically updated upon Activity events.

Type:

androidx.appcompat.app.AppCompatActivity

JavaScript
TypeScript

const foregroundActivity = androidApp.foregroundActivity

const foregroundActivity = androidApp.foregroundActivity

startActivity

The main (start) Activity for the application.

Type:

androidx.appcompat.app.AppCompatActivity

JavaScript
TypeScript

const startActivity = androidApp.startActivity

const startActivity: androidx.appcompat.app.AppCompatActivity = androidApp.startActivity

orientation

Gets or sets the orientation of the application.

Type:

portrait| landscape| unknown

JavaScript
TypeScript

const orientation = androidApp.orientaion

const orientation: 'portrait' | 'landscape' | 'unknown' = androidApp.orientation

systemAppearance

Returns whether the system appearance is dark or light.

Type:

dark| light

JavaScript
TypeScript

const systemAppearance = androidApp.systemAppearance

const systemAppearance: 'dark' | 'light' = androidApp.systemAppearance

paused

Returns true if the main application activity is not running (suspended), otherwise false is returned.

Type:

boolean

JavaScript
TypeScript

const isSuspended = androidApp.paused

const isSuspended: boolean = androidApp.paused

backgrounded

Returns true if the main application activity is in background, otherwise false is returned.

Type:

boolean

JavaScript
TypeScript

const isInBackground = androidApp.backgrounded

const isInBackground: boolean = androidApp.backgrounded

AndroidApplication Methods

registerBroadcastReceiver(intentFilter, onReceiveCallback)

Registers a BroadcastReceiver to be run in the main activity thread. The receiver will be called with any broadcast Intent that matches the intent filter, in the main application thread. For more information, please visit.

Parameter(s) Definition

Parameter(s)	Definition
`intentFilter`	A string containing the intent filter.
`onReceiveCallback`	A callback function that will be called each time the receiver receives a broadcast.

intentFilter

A string containing the intent filter.

onReceiveCallback

A callback function that will be called each time the receiver receives a broadcast.

Since this code is Android specific, first check if isAndroid is true. Use the same for any Android-specific code to avoid code for Android to run on iOS and results in the app crashing.

JavaScript
TypeScript

import { isAndroid } from '@nativescript/core'

if (isAndroid) {
  const receiverCallback = (androidContext, intent) => {
    const level = intent.getIntExtra(android.os.BatteryManager.EXTRA_LEVEL, -1)
    const scale = intent.getIntExtra(android.os.BatteryManager.EXTRA_SCALE, -1)
    const percent = (level / scale) * 100.0
    viewModel.set('batteryLife', percent.toString())
  }

  androidApp.registerBroadcastReceiver(
    android.content.Intent.ACTION_BATTERY_CHANGED,
    receiverCallback
  )
}

import { isAndroid } from '@nativescript/core'

if (isAndroid) {
  const receiverCallback = (
    androidContext: globalAndroid.content.Context,
    intent: globalAndroid.content.Intent
  ) => {
    const level = intent.getIntExtra(android.os.BatteryManager.EXTRA_LEVEL, -1)
    const scale = intent.getIntExtra(android.os.BatteryManager.EXTRA_SCALE, -1)
    const percent = (level / scale) * 100.0
    viewModel.set('batteryLife', percent.toString())
  }

  androidApp.registerBroadcastReceiver(
    android.content.Intent.ACTION_BATTERY_CHANGED,
    receiverCallback
  )
}

getRegisteredBroadcastReceiver(intentFilter)

Gets a registered BroadcastReceiver for the specified intent filter.

Parameters Definition

Parameters	Definition
`intentFilter`	A string containing the intent filter for which the BroadcastReceiver.

intentFilter

A string containing the intent filter for which the BroadcastReceiver.

JavaScript
TypeScript

if (isAndroid) {
  const registerReceiver = androidApp.getRegisteredBroadcastReceiver(intentFilter)
}

if (isAndroid) {
  const registerReceiver: android.content.BroadcastReceiver =
    androidApp.getRegisteredBroadcastReceiver(intentFilter)
}

unregisterBroadcastReceiver(intentFilter)

Unregisters previously registered BroadcastReceiver.

Parameters Definition

Parameters	Definition
`intentFilter`	A string containing the intent filter for which the BroadcastReceiver.

intentFilter

A string containing the intent filter for which the BroadcastReceiver.

JavaScript
TypeScript

if (isAndroid) {
  const registerReceiver = androidApp.getRegisteredBroadcastReceiver(intentFilter)
}

if (isAndroid) {
  const registerReceiver: android.content.BroadcastReceiver =
    androidApp.getRegisteredBroadcastReceiver(intentFilter)
}

Android Activity lifecycles events

JavaScript
TypeScript

applicationModule.AndroidApplication.on('activityResumed', args => {
  //handle the event here
})

Application.AndroidApplication.on('activityResumed', args => {
  //handle the event here
})

Other Android Activity lifecycles events are:

activityCreated
activityDestroyed
activityStarted
activityPaused
activityStopped
saveActivityState
activityResult
activityBackPressed
activityNewIntent
activityRequestPermissions

iOS

iOS Properties

ios

The property gives you the Nativescript wrapper, the iOSApplication object, around the native iOS application instance.

Type:

iOSApplication

JavaScript
TypeScript

const iOSApp = Application.ios

const iOSApp: iOSApplication = Application.ios

rootController

The root view controller for the iOS application.

Type:

UIViewController

JavaScript
TypeScript

const rootController = iOSApp.rootController

const rootController: UIViewController = iOSApp.rootController

window

This property gives the key window, the container for your app views, and one of its roles is to deliver touch events to the views. Views are the user interface items such as button, label or scrollview.

Type:

UIWindow

JavaScript
TypeScript

const rootController = iOSApp.window

const rootController: UIWindow = iOSApp.window

delegate

This returns the class you set (the best place to set it is in the app.js or app.ts, before Application.run()) as a delegate or undefined if you didn’t set any. The iOS system monitors the different states of your application and emits an event at each state. To handle these lifecycle events, you have to write a class that extends UIResponder and implements UIApplicationDelegate classes and set the delegate property to that class. You then overwrite the methods from UIApplicationDelegate to handle the events.

Type:

UIApplicationDelegate| undefined

JavaScript
TypeScript

const MyDelegate = (function (_super) {
  __extends(MyDelegate, _super)
  function MyDelegate() {
    _super.apply(this, arguments)
  }
  MyDelegate.prototype.applicationDidFinishLaunchingWithOptions = function (
    application,
    launchOptions
  ) {
    console.log('applicationWillFinishLaunchingWithOptions: ' + launchOptions)
    return true
  }
  MyDelegate.prototype.applicationDidBecomeActive = function (application) {
    console.log('applicationDidBecomeActive: ' + application)
  }
  MyDelegate.ObjCProtocols = [UIApplicationDelegate]
  return MyDelegate
})(UIResponder)

Application.ios.delegate = MyDelegate

@NativeClass()
class MyDelegate extends UIResponder implements UIApplicationDelegate {
  public static ObjCProtocols = [UIApplicationDelegate]

  applicationDidFinishLaunchingWithOptions(
    application: UIApplication,
    launchOptions: NSDictionary<string, any>
  ): boolean {
    console.log('applicationWillFinishLaunchingWithOptions: ' + launchOptions)

    return true
  }

  applicationDidBecomeActive(application: UIApplication): void {
    console.log('applicationDidBecomeActive: ' + application)
  }
}
Application.ios.delegate = MyDelegate

For a complete list of the iOS lifecycle events, visit UIApplicationDelegate.

orientation

Gets or sets the orientation of the application.

Type:

portrait| landscape| unknown

JavaScript
TypeScript

const orientation = iOSApp.orientaion

const orientation: 'portrait' | 'landscape' | 'unknown' = iOSApp.orientation

systemAppearance

Returns whether the system appearance is dark or light.

Type:

'dark' | 'light' | null (for iOS <= 11)

JavaScript
TypeScript

const systemAppearance = iOSApp.systemAppearance

const systemAppearance: 'dark' \| 'light' \| 'null' = iOSApp.systemAppearance

nativeApp

Returns the reference to the native iOS app.

Type:

UIApplication

JavaScript
TypeScript

const nativeApp = iOSApp.nativeApp

const nativeApp: UIApplication = iOSApp.nativeApp

iOSApplication Methods

addNotificationObserver(notificationName, onReceiveCallback: (notification))

Adds an observer to the default notification center for the specified notification. For more information, please visit.

Parameter(s) Definition

Parameter(s)	Definition
`notificationName:string`	A string containing the name of the notification. Find the possible values here
`onReceiveCallback:(notification: NSNotification) => void`	A callback function that will be called each time the observer receives a notification for which it was registered.

notificationName:string

A string containing the name of the notification. Find the possible values here

onReceiveCallback:(notification: NSNotification) => void

A callback function that will be called each time the observer receives a notification for which it was registered.

JavaScript
TypeScript

const observer = iOSApp.addNotificationObserver(
  'myNotification',
  (notification: NSNotification) => {}
)

const observer: any = iOSApp.addNotificationObserver(
  UIDeviceOrientationDidChangeNotification, // For example
  (notification: NSNotification) => {
    //Handle the notification
  }
)

removeNotificationObserver(observer, notificationName)

Removes the observer for the specified notification from the default notification center.

Parameters Definition

Parameters	Definition
`observer`	The observer that was returned from the addNotificationObserver method.
`notificationName`	A string containing the name of the notification.
`onReceiveCallback`	A callback function that will be called each time the observer receives a notification.

observer

The observer that was returned from the addNotificationObserver method.

notificationName

A string containing the name of the notification.

onReceiveCallback

A callback function that will be called each time the observer receives a notification.

JavaScript
TypeScript

iOSApp.removeNotificationObserver(observer, UIDeviceBatteryStateDidChangeNotification)

iOSApp.removeNotificationObserver(observer, UIDeviceBatteryStateDidChangeNotification)

Cross-platform application events

These are Nativescript events for both platforms.

JavaScript
TypeScript

applicationModule.on('orientationChanged', args => {
  console.log(args.eventName) // orientationChanged
})

Application.on('orientationChanged', (args: ApplicationEventData) => {
  console.log(args.eventName) // orientationChanged
})

Other cross-platform events:

livesync
cssChanged
launch
displayed
suspend
resume
exit
lowMemory
uncaughtError
discardedError
orientationChanged
systemAppearanceChanged
fontScaleChanged

API References

Name Type

Name	Type
@nativescript/core/application	`Module`

@nativescript/core/application

Module

Native Component

Android	iOS
android.app.Application	UIApplication

Android

iOS

android.app.Application

UIApplication