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NativeScript v3.0 Breaking Changes

General notes

We are moving the modules closer to ES6 standard. This introduces few limitations. One of them is modules can no longer export variable, in such cases variables were replaced with get/set functions.

TypeScript

TypeScript projects need TypeScript 2.2 or newer to transpile. You also need to reference the ES6 and DOM libraries. Add this to your tsconfig.json:

{
  "compilerOptions": {
    ...
    "lib": ["es6", "dom"],
    "baseUrl": ".",
    "paths": {
      "*": [
        "./node_modules/tns-core-modules/*",
        "./node_modules/*"]
    }
  }
}

Camera

The camera module is removed. Use nativescript-camera plugin instead.

Location

The location module is removed. Use nativescript-geolocation plugin instead.

Changes in UI Modules

Application

We are using the following import statement for the code samples in this section

import * as application from "tns-core-modules/application";

application.mainEntry was removed.

application.mainModule was removed.

Pass mainModule or mainEntry to application.start method. If you need access to mainEntry use:

  • application.getMainEntry(): NavigationEntry

The string mainModule is implicitly converted to NavigationEntry and set to mainEntry.

application.resources was removed, use get/set methods:

  • application.getResources(): any
  • application.setResources(res: any)

application.cssFile was removed, use get/set methods:

  • application.getCssFileName(): string
  • application.setCssFileName(file: string)

Removed application callback methods:

  • application.onSuspend()
  • application.onResume()
  • application.onExit()
  • application.onLowMemory().

Use the corresponding events such: application.on(“suspend”, (args: application.ApplicationEventData) => … );

Removed all android specific callback methods. For example instead of application.android.onActivityResult(…) use application.android.on("activityResult", (eventData) => …)

Console

console.dump() removed, use console.dir() instead.

KeyframeAnimation

Changed method keyframeAnimationFromInfo(info: KeyframeAnimationInfo, valueSourceModifier: number): KeyframeAnimation to KeyframeAnimation.keyframeAnimationFromInfo(info: KeyframeAnimationInfo): KeyframeAnimation. ValueSource no longer needed.

Observable

Observable constructor that accepts an object is removed. Use observableModule.fromObject(obj) method instead.

SegmentedBar

Removed method insertTab(). You can use items property for setting additional tabs. Removed method getValidIndex() - it was intended for internal use only.

The 'items' property is of type SegmentedBarItem[]. Items should be created using the SegmentedBarItem constructor.

Old code:

let firstItem =  {"title": "first"};
segmentedBar.items = [ firstItem ];

New code:

let firstItem = new SegmentedBarItem();
firstItem.title = "first";
segmentedBar.items = [ firstItem ];

Span

Removed methods and properties. These were for internal use only and not needed any more:

  • parentFormattedString property
  • updateSpanModifiers(parent: formattedString.FormattedString): void;
  • beginEdit(): void;
  • endEdit(): void;

TabView

Removed properties of TabView class (ui/tab-view module):

  • selectedColor - use selectedTabTextColor instead.
  • tabsBackgroundColor - use tabBackgroundColor instead.
  • textTransform - textTransform can be set on the individual TabViewItems instead on the TabView

TextField & TextView (Android)

Setting text-transform property on these controls will not change the text inside them. In case you want to transform the text you should do it before setting it to text property.

Trace

The enabled exported variable is replaced with getter function: isEnabled(). You can still use the enable() and disable() methods to enable/disable tracing.

Utils

We are using the following import statement for the code samples in this section

import * as utils from "tns-core-modules/utils/utils";

Removed utils.parseJSON(source: string) method – use JSON.parse() instead.

Removed the following functions. These were for internal use only and are not needed any more:

  • utils.copyFrom(source: any, target: any)
  • utils.ad.setTextTransform(view, value: string)
  • utils.ad.setWhiteSpace(view, value: string)
  • utils.ad.setTextDecoration(view, value: string)
  • utils.ad.getTransformedString(textTransform: string, view, stringToTransform: string): string
  • utils.ios.getTransformedText(view, source: string, transform: string): string
  • utils.ios.setWhiteSpace(view, value: string, parentView?: any)
  • utils.ios.setTextAlignment(view, value: string)

View

Property cssClass removed, use className instead.

The _createUI() method is renamed to createNativeView(). It should now return a native view instance instead of setting it locally. Read more here.

The _onBindingContextChanged() method is removed. If you are using this to set the bindingContext of an object and that object is extending ViewBase, it will automatically have its bindingContext set. In case you need to know when bindingContext is changed you could add handler to this.on("bindingContextChange", handlerMethod, this).

VerticalAlignment - "center" is removed from Typescript definition files but is still supported through CSS/XML. In code – use "middle" instead of center.

WebView

The url property of WebView is removed, use src instead.

Property System

The way View properties are defined, stored and applied to native view is completely re-written and this is the area where most of the breaking changes and performance improvements are.

Properties Types in Modules 3.0

There are several type of Properties in modules 3.0:

  • Property – property defined on ViewBase or another view class. These are properties like id on ViewBase or text on Label.
  • CssProperty – property defined on Style type. These are properties that could be set in CSS.
  • InheritedCssProperty - property defined on Style type. These are inheritable CSS properties that could be set in CSS and propagates value on its children. These are properties like FontSize, FontWeight, Color, etc.

Events raised when property value change

One significant change is that properties before 3.0 were raising two events when a value is changed - propertyChange and propertyName + Change (like textChange). The second event was added at some point to make module compatible with Angular. With 3.0 we removed propertyChange event and left only the second event. This was done in order to improve performance of our property system. This also leads to cleaner code (no need to listen for every propertyChange and then check the name of the poperty that raised the event).

With 3.0 if you want to get notification when some property value change you have to specify the propertyNameChange as eventName to addEventListener method (like textField.addEventListener('textChange', handler...)).

NativeView property

There is a new property nativeView in ViewBase class. It is recommended to use nativeView instead of ios and android properties. The ios and android properties are left for compatibility, however all view-lifecycle methods and native property callbacks (explained below) should work with the nativeView property.

Property Example

Here is how to define text (view property) and text-align (css property) for the text-View

my-text-view-common.ts with cross-platform code

import { View, Property, CssProperty, InheritedCssProperty, Style, } from "tns-core-modules/ui/core/view";

export class MyTextViewCommon extends View {
  ...
  // Defined property to make typescript happy. Not needed in pure JS.
  text: string;

  // Css properties are defined on the Style when registered
  // You can optionally expose the property on the View class also
  get textAlignment(): TextAlignment {
    return this.style.textAlignment;
  }
  set textAlignment(value: TextAlignment) {
    this.style.textAlignment = value;
  }
}

// Define textProperty and register it
export const textProperty = new Property<MyTextViewCommon, string>({ name: "text", defaultValue: "" });
textProperty.register(MyTextViewCommon);

// Define and register the "text-align" CSS property
export type TextAlignment = "left" | "center" | "right";
export const textAlignmentProperty = new InheritedCssProperty<Style, TextAlignment>({
    name: "textAlignment",
    cssName: "text-align",
    valueConverter: TextAlignment.parse
});
textAlignmentProperty.register(Style);

Every property which type is not string should define valueConverter. Even properties that are of type string but allow only some strings (like enums) should define valueConverter and either convert from string or throw an exception in case value is not valid. If equalityComparer is not defined we use === to compare currentValue and newValue. This will work only for simple property types like boolean, string and number. For other types it is recommended to specify equalityComparer.

In the platform specific implementation use getDefault and setNative symbols from the property object (ex. textProperty), to define how this property is applied to native views.

getDefault method is called just once before the first call to setNative so that we know what is the default native value for this property. The value that you return will be passed to setNative method when we decide to recycle the native view. Recycling the native view of control is done only if recycleNativeView field is set to true.

my-text-view.android.ts with android specific implementation:

import {
    MyTextViewCommon, textAlignmentProperty, textProperty, ...
} from "./my-text-view-common";

export class MyTextView extends MyTextViewCommon {
  ...

  // text property
  [textProperty.getDefault](): string {
    return '';
  }
  [textProperty.setNative](value: string) {
    this.nativeView.setText(value);
  }

  // text alignment property
  [textAlignmentProperty.getDefault](): TextAlignment {
    let nativeGravity = this.nativeView.getGravity();
    // Extract the align value based on the native gravity
    return this.extractAlignmentFromGravity(nativeGravity); 
  }

  [textAlignmentProperty.setNative](value: TextAlignment) {
    let verticalGravity = this.nativeView.getGravity() & android.view.Gravity.VERTICAL_GRAVITY_MASK;
    // set the native gravity for the view base on the property value
    switch (value) {
      case "left":
        this.nativeView.setGravity(android.view.Gravity.LEFT | verticalGravity);
        break;
        ...
    }
  }
}

Removed Classes and Methods

The way of defining properties using Styler class and property handlers are no longer valid.

  • "ui/styling/style" modules:
    • Styler class
    • StylePropertyChangedHandler class
    • IgnorePropertyHandler class
    • registerHandler(property: Property, handler: StylePropertyChangedHandler, className?: string)
    • registerNoStylingClass(className);
    • getHandler(property: Property, view: View): StylePropertyChangedHandler;
  • "ui/core/dependency-observable" module
    • Property
    • PropertyEntry
    • DependencyObservable
  • “ui/builder/special-properties” module removed
  • "ui/styling/style-property" module removed.

View Class Hierarchy

The class hierarchy prior 3.0 was:

Observable > DependencyObservable > Bindable > ProxyObject > View

In 3.0 the redesign of the property system allowed us to collapse it to:

Observable > ViewBase > View

Bindable(“ui/core/bindable” module), ProxyObject (“ui/core/proxy” module) and DependencyObservable ("ui/core/dependency-observable" module) are removed.

Consider using View, ViewBase or Observable instead.

Property Types

As a part of the refactoring we have changed the types of many properties. The reasons for the changes:

  • Make better use of the TypeScript typings.
  • Support for units (dip, px, %) for properties like width, height, margin.

Here is a list of view and style properties that have their types changes:

class.property old type new type
Style.width number PercentLength
Style.height number PercentLength
Style.minWidth number Length
Style.minHeight number Length
Style.translateX number Length
Style.translateY number Length
Style.margin string string | PercentLength
Style.margin[Left/Right/Top/Bottom] number PercentLength
Style.padding string string | Length
Style.padding[Left/Right/Top/Bottom] number Length
Style.borderWidth string | number string | PercentLength
Style.border[Left/Right/Top/Bottom]Width number Length
Style.border[TopLeft/TopRight/BottomLeft/BottomRight]Radius number Length
ListView.rowHeight number Length

Many of the Style properties are also defined on the View class - the changes in the types are the same.

Note: The new types are backwards compatible when it comes to setters. For example:

let image = new Image();
// still works - sets the width in dips
image.width = 100; 

// with 3.0 - sets width in pixels
image.width = { value: 100, unit: "px" };

You have to be careful when getting the value - you might get a complex object instead of number.

Enumerations

Enumeration from ui/enums modules are not used anymore. Most ot the properties that accepts specific strings are defined directly with the allowed values: export type TextAlignment = "initial" | "left" | "center" | "right"; TypeScript will warn in case you set invalid value.

View Life-cycle

With 3.0 we are introducing nativeView recycling. With nativeView recycling we aim to reduce instantiation of native views which is really expensive operation in Android. In order to be able to recycle it, we need all properties exposed from the View to be of our new property system.

In short, we have method that gets the default value for a property which is get the first time a property value is changed. Once we know that our View is not needed anymore we will reset the native view to its original state and put it in a map where some future Views of the same type could reuse it. There are 3 new important methods:

  • createNativeView(): Object; - method to create and return the native view instance.
  • initNativeView(): void; - method to initialize the native view. Attach handlers, owner, etc.
  • disposeNativeView(): void; - method to detach owner and eventually to reset manually the native view.

Iterating Over View Children

There are two methods that allow you to traverse view-hierarchy:

For getting View children use:

public eachChildView(callback: (child: View) => boolean): void

This method was previously known as _eachChildView(). It will return View descendants only. For example TabView returns the view of each TabViewItem because is TabViewItem is of type ViewBase.

Getting ViewBase children use:

public eachChild(callback: (child: ViewBase) => boolean): void;

This method will return all views including ViewBase. It is used by the property system to apply native setters, propagate inherited properties, apply styles, etc. In the case of TabView – this method will return TabViewItems as well so that they could be styled through CSS.