Recently during the Google Developer Days Conference in China that was held on September 10, 2019, Flutter 1.9 was released along with the updated Dart 2.5 programming language.h

最近在2019年9月10日在中国举行的Google开发人员日会议上，Flutter 1.9与更新的Dart 2.5编程语言一起发布了。

The major highlights from the conference can be summed into three major points:

会议的主要亮点可以概括为三个要点：

• Google has announced Dart 2.5 programming update and a new Flutter 1.9 Version upgrade.
  Google已宣布Dart 2.5编程更新和Flutter 1.9版本的新升级。
• Dart 2.5 will support calling C code and intelligent code completion.
  Dart 2.5将支持调用C代码和智能代码完成。
• Flutter 1.9 will support iOS 13, macOS Catalina, and new Material widgets.
  Flutter 1.9将支持iOS 13，macOS Catalina和新的Material小部件。

In this blog, I am going to discuss the major pointers in detail for you to understand the highlights and updates in detail!

在本博客中，我将详细讨论主要指标，以便您详细了解重点内容和更新！

Let’s begin!

让我们开始！

Dart 2.5作为编程语言有什么用？ (What’s in store for Dart 2.5 as a programming language?)

Dart is a Google borne programming language that has been used to develop mobile, web and desktop based applications. It is an object-oriented, class defined, garbage collected language with a C-style syntax, which is used to optionally compile into JavaScript.

Dart是Google传播的编程语言，已用于开发基于移动，Web和桌面的应用程序。 它是一种面向对象的，类定义的，垃圾回收的语言，具有C样式的语法，可用于选择性地编译为JavaScript。

The latest version of Dart 2.5 comes with these major highlights:

Dart 2.5的最新版本具有以下主要亮点：

->支持使用Dart FFI库直接通过Dart调用C代码： (-> Support for Calling C Code straight through Dart using Dart FFI Library:)

Developers who have knowledge about low-level programming languages will be excited from this announcement. The event also saw the launch of dart:ffi library, the preview of which allows calling into C code directly from Dart and Flutter.

知道低级编程语言的开发人员将对此感到兴奋。 该活动还启动了dart：ffi库，该库的预览允许直接从Dart和Flutter调用C代码。

As a result, any app developed using the programming language and framework would have access to system APIs and libraries written in C for Android NDK and desktop platforms.

结果，任何使用编程语言和框架开发的应用都可以访问用C语言编写的，用于Android NDK和桌面平台的系统API和库。

Till now, calling C straight from Dart was possible through deep integration into the Dart VM with the help of native extensions. However, Google has arrived with a new mechanism that enables greater performance, better ease of approach and usability.

到现在为止，借助于本机扩展，可以通过深度集成到Dart VM中来直接从Dart调用C。 但是，Google推出了一种新机制，该机制可以提高性能，简化方法和提高可用性。

In the latest update, Dart-C interop will enable the following two cases:

在最新更新中，Dart-C互操作将启用以下两种情况：

1. Calling into a system API supported by C on the host OS.
   在主机OS上调用C支持的系统API。
2. The calling into library is supported by C that’s either cross-platform for a single OS.
   C语言支持对单个库的跨平台跨库调用。

The new dart:ffi library is now ready and can be tried on a Dart dev channel or Flutter master channel.

新的dart：ffi库现已准备就绪，可以在Dart开发人员通道或Flutter主通道上尝试。

->利用机器学习实现智能代码完成： (-> Leverage Machine Learning for Intelligent Code Completion:)

The power of Machine Learning is here to help Flutter and Dart apps with precision. Dart 2.5 brings it with the preview of code completion system which is ML based.

机器学习的强大功能可帮助您精确地帮助Flutter和Dart应用程序。 Dart 2.5带来了基于ML的代码完成系统的预览。

This new system is based on TensorFlow Lite and the open source Dart repositories available on Github. It works by attempting to suggest relevant options.

这个新系统基于TensorFlow Lite和Github上的开放源代码Dart存储库。 它通过尝试建议相关选项来起作用。

This is a welcoming change that keeps in mind the list of possible completions in typed programming language. TensorFlow Lite trains a member occurrence model by analyzing the heaps of open source Dart Code Compilations.

这是一个值得欢迎的更改，请牢记键入的编程语言中可能完成的列表。 TensorFlow Lite通过分析开源Dart Code Compilation的堆来训练成员出现模型。

Therefore, this model is used to predict the next symbol as the API continues to grow and the developer types.

因此，随着API的持续增长和开发人员的类型，该模型可用于预测下一个符号。

This preview is a part of the Dart analyzer, which makes the code completion accessible across all editors that support Dart. These include Android Studio, Visual Studio Code, and IntelliJ, too.

此预览是Dart分析器的一部分，该分析器使支持Dart的所有编辑器都可以访问代码完成。 其中也包括Android Studio，Visual Studio Code和IntelliJ。

->常量表达式及其喜欢的地方： (-> Constant Expressions and the Likes of it:)

Last but not the least, the new version of Dart supports a lot more ways to support constant expressions. Till now, Dart has been supporting the creation of constant variables and values.

最后但并非最不重要的一点是，新版本的Dart支持更多的方式来支持常量表达式。 到目前为止，Dart一直支持常量变量和值的创建。

However, the support for constant expressions came with limits.

但是，对常量表达式的支持是有限度的。

With the new update, there are now new ways to do the same. It will include ways to implement casts for better control flow and collection spread features.

有了新的更新，现在有新的方法可以做到这一点。 它将包括实现强制转换的方法，以更好地控制流和集合传播功能。

Google is now preparing for the next update with extension methods that would allow non-nullable references by default and has improved the support for concurrency. Rich migration tools for existing code is the tech giant’s latest area of interest and investment.

Google现在正在准备使用扩展方法进行下一次更新，该扩展方法将默认允许非空引用，并改进了对并发的支持。 现有代码的丰富迁移工具是该技术巨头最新的关注和投资领域。

Flutter 1.9的新增功能？ (What’s New in Flutter 1.9?)

Flutter is an app development framework which has been running in the league with the competitor’s Facebook React Native.

Flutter是一个应用程序开发框架，已与竞争对手的Facebook React Native一起运行。

As it was discussed previously, the new Flutter version 1.9 fully supports iOS 13 and macOS Catalina, and has arrived with more advanced tools, better material widget, and exciting Dart-based features.

如前所述，新的Flutter 1.9版完全支持iOS 13和macOS Catalina，并提供了更多高级工具，更好的材质小部件和令人兴奋的基于Dart的功能。

The release has been estimated well with the official launch of iOS 13 and was built keeping in mind the latest UI features. Also, Flutter 1.9 has been built for absolute macOS Catalina support including that for Xcode 11.

该版本在iOS 13正式发布时得到了很好的估计，并且在构建时考虑了最新的UI功能。 此外，Flutter 1.9的构建是为了对macOS Catalina绝对支持，包括对Xcode 11的支持。

Flutter App Development has always been in rage and there have been companies who are pioneer in app development in Flutter.

Flutter应用程序开发一直风靡一时，有些公司是Flutter应用程序开发的先驱。

Some of the prominent highlights have been listed below:

下面列出了一些突出的亮点：

-> Flutter For Web： (-> Flutter For Web:)

As mentioned earlier, Google has fused Flutter Web Repository with the main repository. In other terms, we have a unified Flutter Repository which makes it possible to develop applications for desktop, mobile and web using the same codebase.

如前所述，Google已将Flutter Web存储库与主存储库融合在一起。 换句话说，我们有一个统一的Flutter存储库，这使得使用相同的代码库为台式机，移动设备和Web开发应用程序成为可能。

Now, when flutter developers create a project, the framework would create a web runner using a minimal web/index.html file which bootstraps the web compiled code.

现在，当开发人员创建项目时，该框架将使用最小的web / index.html文件创建Web运行程序，该文件会引导Web编译的代码。

This very file would enable using either Flutter CLI tool or the IDE plugins so developers can run and edit Flutter applications on the web. Although the change is in the initial stage, there is still scope for further advancements.

该文件将启用Flutter CLI工具或IDE插件，以便开发人员可以在Web上运行和编辑Flutter应用程序。 尽管更改处于初始阶段，但仍有进一步发展的空间。

->多种语言支持： (-> Multiple Language Support:)

Flutter has gone all out with this release. It has also added support for 24 languages worldwide, something that was totally missing in the previous versions.

Flutter在此版本中全力以赴。 它还增加了对全球24种语言的支持，而以前的版本完全没有这种支持。

These include Albanian, Afrikaans, Amharic, Azerbaijani, Assamese, Bengali, Basque, Belarusian, Burmese, Gujarati, Georgian, Icelandic, Kyrgyz, Kannada, Lao, Malayalam, Macedonian, Nepali, Oriya, Punjabi, Sinhalese, Telugu, Uzbek, and Zulu.

其中包括阿尔巴尼亚语，南非语，阿姆哈拉语，阿塞拜疆语，阿萨姆语，孟加拉语，巴斯克语，白俄罗斯语，缅甸语，古吉拉特语，格鲁吉亚语，冰岛语，吉尔吉斯语，卡纳达语，老挝语，马拉雅拉姆语，马其顿语，尼泊尔语，奥里亚语，旁遮普语，僧伽罗语，泰卢固语，乌兹别克语和祖鲁语。

->支持iOS 13和macOS Catalina： (-> Supporting iOS 13 and macOS Catalina:)

Google is wishing to make Flutter complement the Xcode 11 build system. That’s why Flutter 1.9 is ready for iOS 13 and macOS Catalina.

Google希望让Flutter成为Xcode 11构建系统的补充。 这就是为什么Flutter 1.9可以用于iOS 13和macOS Catalina的原因。

Google has upped the game for end-to-end tooling experience to enable 64-bit support across the toolchain and make platform dependencies simpler.

Google提升了游戏的端到端工具体验，以在整个工具链中提供64位支持并简化平台依赖关系。

Apart from this, Flutter 1.9 supports the draggable toolbar of iOS 13 including the long-press, drag from right features along with vibration feedback.

除此之外，Flutter 1.9还支持iOS 13的可拖动工具栏，包括长按，从右侧拖动功能以及振动反馈。

->支持新材料小部件： (-> Support for New Material Widgets:)

Flutter 1.9, has also been the flag bearer for new material design widgets. Material is a leading open-source design system implemented to enable interactive user experiences across the platform. It is comprehensive and flexible at the same time.

Flutter 1.9也一直是新材料设计小部件的标志。 Material是一个领先的开源设计系统，旨在实现跨平台的交互式用户体验。 它既全面又灵活。

In the new version for Flutter, several new widgets have been introduced. For instance, the text and icon widgets have been combined in the ToggleButtons widget to create a set of customizable buttons.

在Flutter的新版本中，引入了几个新的小部件。 例如，文本和图标小部件已组合到ToggleButtons小部件中，以创建一组可自定义的按钮。

With the ColorFiltered Widget, you can address the color accessibility for color blind people who are among your potent users.

使用ColorFiltered Widget，您可以为有力用户中的色盲用户解决颜色可访问性问题。

There have been many flutter app coders who will ensure efficiency and transparency while executing and operating codes.

有许多颤抖的应用程序编码器 ，它们将在执行和操作代码时确保效率和透明度。

->工具链的改进： (-> Improvements in Toolchain:)

With Flutter 1.9, the new projects would default to Swift instead of objective-C for iOS projects and Kotlin instead of Java for Android Projects for the base code. It will eliminate the manual work that has been required for adding packages written within Swift to an application.

对于Flutter 1.9，对于基础项目，新项目将默认为Swift而不是iOS项目的Objective-C和Kotlin而非Android项目的Java。 它将消除将Swift中编写的包添加到应用程序所需的手动工作。

Swift 5, being ABI stable, its dynamic libraries will no longer require distribution packages for iOS 12.2 onwards, thus minimizing the size of Swift apps. Also, Kotlin has been the most preferred language for Android projects now.

Swift 5是ABI稳定的，其动态库将不再需要iOS 12.2及更高版本的分发包，从而最小化了Swift应用程序的大小。 而且，Kotlin一直是Android项目最喜欢的语言。

Thus, with an option to revert to Objective-C or Java, these new toolchain improvements in Flutter 1.9 seems just right.

因此，通过选择还原为Objective-C或Java，Flutter 1.9中的这些新工具链改进似乎是正确的。

Additionally, Google is working on improving error messages in Flutter to make them more concise, readable and actionable.

此外，Google正在努力改进Flutter中的错误消息，以使其更加简洁，可读性和可操作性。

You can refer to Techtimes for such technical updates & reviews.

您可以参考Techtimes以获得此类技术更新和评论。

尾注： (Ending Note:)

Google Developers Day 2019 has seen a lot of changes in Flutter and Dart and the developer community is certain to welcome the changes with arms wide open.

2019年Google Developers Day在Flutter和Dart中发生了许多变化，开发人员社区肯定会敞开双臂欢迎这些变化。

A great time is expected for flutter developers who are enthusiastic about the technology to be worked upon. Flutter App Development will see a constant rise after the updates have been released in GDD 2019.

对于热衷于要开发的技术的开发者来说，这将是一个美好的时光。 在GDD 2019中发布更新之后，Flutter应用程序开发将持续增长。

祝好运！ (Good Luck!)

翻译自: https://habr.com/en/post/483178/