NativeScript 1.5.0 发布跨平台移动开发

NativeScript 1.5.0 发布，此版本更新内容：

重大改进

修改验证器 XSD 模式的 XML 命名空间 (xmlns)，从xmlns="http://www.nativescript.org/tns.xsd" 修改为xmlns="http://schemas.nativescript.org/tns.xsd"

###Bug 修复

(#1089) http toString will raise error if response cannot be converted to string
(#1082) Null reference exception in view.android.setOnTouchListener method
(#1081) file-system writeTextSync will now unlock the file when it is done writing
(#1038) WebView with HTML string source does not render on old Android
(#1028) [iOS] SelectedIndex property of the TabView widget does not work
(#1021) page.loaded and page.navigatedTo events are fired twice on iOS
(#1019) search-bar color not applied correctly
(#1012) TextField/TextView CSS color not applied to cursor
(#1010) Slider CSS color/background-color support
(#1007) When application.start() is called twice on iOS, a meaningful error should be thrown
(#1004) ActivityIndicator CSS color support
(#1000) Border radius is not working on Android API 17
(#998) web-view images now will be loaded correctly with base url
(#993) CSS does not support new lowercase element names
(#990) Android 6 Webview onReceivedError
(#986) [iOS] The switch widget does not show up on the page
(#973) iOS owner pattern changed to use WeakRef in order to prevent memory leaks
(#966) Observable emits two propertyChange events when created with JSON
(#963) Always set base URL in WebView
(#955) Gestures event arguments for Android fixed
(#941) global.ios missing (consistency)
(#940) ListView: Inconsistency retrieving bindingContext in tap handler
(#936) Subsequent animation of transition and rotation or scale will appear jumpy in iOS
(#889) vertical-align css inconsistency
(#820) The x and y components of an Android translate or scale animation are not animated together when delay is specified
(#801) Chained animations lose state on iOS
(#789) Error in Page Navigating Events order
(#781) ios page.showModal platform inconsistancies & bugs
(#715) Frame crashes on app restore occasionally
(#642) Ability to style other native widgets

###新特性

(#1001) Embed utility fonts: Awesome, Icons, etc
(#1102) Ability to specify an animation easing, i.e. curve in a platform-independent manner
(#1086) This will now allow the dialog to call the resolve function when cancelled by clicking outside
(#1057) Expose scroll event on ScrollView
(#1048) Event for start/end of an event
(#1041) Support binding for class property of views
(#1034) Support CSS white-space: nowrap and normal
(#1020) DatePicker and TimePicker stylers added
(#1014) Button wrapText property
(#977) Smarter LiveSync
(#954) added simple showModal() overload
(#926) Context as to whether a navigation was back or not
(#922) Feature request: Add loading wheel to Dialogs module
(#875) CSS feature request: text-decoration
(#856) Android 6 support
(#849) Implement dismissSoftInput() for search-bar
(#841) Distribute TypeScript definitions
(#767) Change Android navigation and tabs title color
(#727) Provide a way to get a reference to the currently showing modal page instance
(#693) ListView – the position of the item after scroll down is not correct
(#597) Some Complex Properties are Inconsistent with rest of API – Discussion
(#551) Ship a verified image picker plugin
(#364) Ability to use built-in system icons on ActionBarItems

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NativeScript 可以使用 Javascript，CSS, XML 创建真正的 Native 跨平台应用，支持 iOS Android，NativeScript 将您的跨平台代码翻译成目标平台的代码。

UI 使用 XML 描述，CSS 样式，在编译时将 UI 转化成本地原生代码,最终得到正在的 Native 原生应用。

Telerik 公开了用于创建安卓、iOS和Windows Universal跨平台原生应用的框架，NativeScript 的公共访问权限。

NativeScript既不是一种新型的JavaScript语言，也不是原生功能的封装器，它包括一个JavaScript运行时环境和一种将 JavaScript调用转化为原生调用的机制。用JavaScript（或TypeScript，CoffeeScript等）语言编写应用，之后在安卓平台用V8，在iOS和Windows Phone上用WebKit JavaScriptCore解释应用。然后，NativeScript运行时环境找到原生的目标API，将JS数据类型转化为相应的原生类型，然后调用原生API，并将得到的结果值返回，具体流程如下图所示：、

举例来说，在安卓平台上创建文件对象var file = new java.io.File(path);的步骤如下：

用V8解释代码
根据原数据确定相应的原生方法调用。原数据是在各个平台上预先构建的提供类型和方法签名的全部可用API集合。
类型转换模块将JavaScript的String类型转换为一个java.lang.String对象
运行时环境为java.io.File创建一个代理对象
通过该代理将对原有JS File对象的调用委托给相应的Java实例

据Telerik介绍，与纯原生代码相比NativeScript运行时环境会带来大概10%的性能损失。

NativeScript可以将其所支持平台上的任意原生API作为目标，包括传感器接口API和用Objective C，Java或.NET编写的第三方库。UI组件是原生的，UI事件由在JavaScript代码中声明的原生处理程序处理，如View.OnClickListener，UIControl.addTarget。

为了避免开发者需要对三个支持的平台有深入的理解，该框架包含了一个抽象与原生代码连接的NativeScript模块层（NativeScript Modules Layer，NML），可以自动将JavaScript调用转化为原生调用。NML包含如下模块：Application，Camera，Color，Console，Data，File System，HTTP，Imaging，Local Settings，Location，Timer，UI。开发者并未受限于只能使用NML，也可以访问任意原生API。

NativeScript其它一些功能简单列示如下：