Flutterは何ができるんですか？

Flutterは開発者に、AndroidとiOS両方のクロスプラットフォームでハイパフォーマンスなアプリの、 ビルドやデプロイを行う簡単で生産的な方法を提供します。

Flutterはユーザーに、美しく、高速で、イライラしないアプリケーション体験を提供します。

Flutterは何を提供していますか？

Flutterは3つのメインコンポーネントを持っています:

  • 強く最適化されたモバイルファーストな2Dレンダリングエンジン(特にテキストのサポートに優れています)
  • 機能的(functional)で反応の良い(reactive)フレームワーク(これは任意で、あなたの好きなフレームワークを利用できます)
  • マテリアルデザインのウィジェットのセット(これは任意で、あなたの好きなウィジェットを利用できます)、ライブラリ、ツール、そしてAtomのプラグイン。

Flutterはどこがユニークですか？

Flutterが他のモバイルクロスプラットフォームアプリと最も異なる点は、 WebViewもデバイス付属のOEMウィジェットも利用していないということです。 代わりに独自のハイパフォーマンスなレンダリングエンジンをウィジェットの描画に利用しています。

Flutterは開発者に高い生産性と高速な開発体験、高速なランタイムとエンジン性能、 そして美しいアプリを作るための美しいデザインのウィジェットを提供します。

なぜFlutterを学んだほうが良いのですか？

FlutterはAndroidとiOSの両方で動く美しいアプリを、ひとつのコードベースから扱う簡単な方法です。 Flutterは 編集/デバッグ のサイクルを楽しく、抵抗のないワークフローで開発者に提供します。

What are Flutter’s guiding principles?

We believe that:

  • In order to reach every potential user, developers need to target multiple mobile platforms.
  • HTML and WebViews as they exist today make it challenging to consistently hit high frame rates and deliver high-fidelity experiences, due to automatic behavior (scrolling, layout) and legacy support.
  • Today, it’s too costly to build the same app multiple times: it requires different teams, different code bases, different workflows, different tools, etc.
  • Developers want an easier, better way to use a single codebase to build mobile apps for multiple target platforms, and they don’t want to sacrifice quality, control, or performance.

We are focused on three things:

  • Control - Developers deserve access to, and control over, all layers of the system. Which leads to:
  • Performance - Users deserve perfectly fluid, responsive, jank-free apps. Which leads to:
  • Fidelity - Everyone deserves precise, beautiful, delightful mobile app experiences.

FlutterとSkyはどのような関係ですか？

Skyは初期のFlutterのコードネームです。

What devices and OS versions does Flutter run on?

Flutter apps run on Android Jelly Bean, v16, 4.1.x or newer, and iOS 5 or newer. We test on a variety of low-end to high-end phones and tablets, but we don’t yet have an official device compatibility guarantee.

What technology is Flutter built with?

Flutter is built with C, C++, Dart, Skia (a 2D rendering engine), Mojo IPC, and Blink’s text rendering system. See this architecture diagram for a better picture of the main components.

How does Flutter run my code on Android?

The engine’s C/C++ code is compiled with Android’s NDK, and the majority of the framework and application code is running on the Dart VM. The Dart VM generates JIT-compiled optimized native code on the device. (In other words, the Dart VM is not an interpreter.)

How does Flutter run my code on iOS?

The engine’s C/C++ code is compiled with LLVM, and any Dart code is AOT-compiled into native code. The app runs using the native instruction set (no interpreter is involved).

FlutterはWEB上で動作しますか？

いいえ。FlutterのWEBバージョンは現在予定されていません。

FlutterアプリをビルドするにはどのOSが必要ですか？

FlutterはLinuxとMacをサポートしています。Windowsサポートは計画段階です。

どのような種類のアプリをFlutterで作ることができますか？

FlutterはAndroidとiOSの両方で動作する2Dアプリに最適化されています。 マテリアルデザインを利用するアプリは特にFlutter向きです。

What kind of app performance can I expect?

You can expect excellent performance. Flutter is designed to help developers easily achieve a constant 60fps. Flutter apps run via natively compiled code, no interpreters are involved.

Can I use Flutter to build desktop apps?

We are focused on mobile-first use cases. However, Flutter is open source and we encourage the community to use Flutter in a variety of interesting ways.

Can I use Flutter inside of my existing native app?

Yes, you can embed a Flutter view in your existing Android or iOS app. You can learn more about this at [[docs coming soon]]. If you want to do this, we encourage you to email our mailing list: flutter-dev@googlegroups.com.

Can I access native services and APIs like sensors and local storage?

Yes. Flutter gives developers access to any service or API that the host operating system provides, via Mojo’s IPC system. You can learn more about this at [[docs coming soon]]. If you want to do this, we encourage you to email our mailing list: flutter-dev@googlegroups.com.

Can I interop with my mobile platform’s default programming language?

Yes. Flutter uses Mojo’s IPC system to interop between Flutter’s app code and the host operating system. You can learn more about this at [[docs coming soon]]. If you want to do this, we encourage you to email our mailing list: flutter-dev@googlegroups.com.

Does Flutter come with a framework?

Yes! Flutter ships with a functional-reactive style framework, inspired by React. However, Flutter’s framework is designed to be optional and layered. Developers can choose to use only parts of the framework, or a different framework.

Does Flutter come with widgets?

Yes! Flutter ships with a set of high quality Material Design widgets, layouts, and themes. You can see a collection of those widgets at [[docs coming soon]]. Of course, these widgets are optional. Flutter is designed to make it easy to create your own widgets, or customize the existing widgets.

Can I extend and customize the bundled widgets?

Absolutely. Flutter’s widget system was designed to be easily customizable. You can see an example of that at [[docs coming soon]].

Does Flutter come with a testing framework?

Flutter apps are tested with the test package. Learn more about testing with Flutter here [[docs coming soon]].

Does Flutter come with a dependency injection framework or solution?

Not at this time. Please share your ideas at flutter-dev@googlegroups.com.

Does Flutter come with a reflection/mirrors system?

Not at this time. Because Flutter apps are pre-compiled for iOS, and binary size is always a concern with mobile apps, we disabled dart:mirrors. We are curious what you might need reflection/mirrors for, please email us at flutter-dev@googlegroups.com.

How do I do internationalization (i18n), localization (l10n), and accessibility (a11y) in Flutter?

These capabilities are very much on our radar, but we have not yet started on the APIs. We are currently building the core framework with these capabilities in mind.

How do I write parallel and/or concurrent apps for Flutter?

Flutter supports isolates. Isolates are separate heaps in Flutter’s VM, and they are able to run in parallel (usually implemented as separate threads). Isolates communicate by sending and receiving asynchronous messages. Flutter does not currently have a shared-memory parallelism solution, although we are evaluating solutions for this.

Can I use JSON/XML/protobuffers/etc with Flutter?

Absolutely. There are libraries in pub.dartlang.org for JSON, XML, protobufs, and many other utilities and formats.

How do I write well-styled code for Flutter?

Flutter has an opinionated style guide, which we encourage you to check out.

Does Flutter use my system’s OEM widgets?

No. Flutter provides a set of Material Design widgets, managed and rendered by Flutter’s framework and engine.

How do I deploy a Flutter app?

Flutter apps are most commonly deployed via the mobile platform’s store (such as Apple’s App Store and Google’s Play Store). We plan to deliver tools to easily to generate an .ipa and easily generate an .apk.

Can I update my app over the network, outside of the Play Store?

Yes. On Android, you can update your app over the network (via HTTP), without first publishing to the Play Store. This can be useful because it doesn’t bother the user with a notification, ensures your users are on the latest version, makes it easier to run A/B experiments, and more.

Unfortunately, due to iOS restrictions, updating your Flutter app over the network is not possible. We are curious how much you use this feature, please let us know at flutter-dev@googlegroups.com.

What if I don’t want to build my app with Material Design?

Flutter’s widget system is designed to be extensible, and it’s supported and possible to create your own set of widgets using our base classes.

Does Flutter work with any editors or IDEs?

We are building a Flutter plugin for Atom. Today, it can syntax highlight, code complete, refactor, launch apps, create new apps from a template, show type hierarchies, jump to definition, and more.

Can I build 3D (OpenGL) apps with Flutter?

Today we don’t support for 3D via OpenGL ES or similar. We have long-term plans to expose an optimized 3D API, but right now we’re focused on 2D.

How big is the Flutter engine?

As of November, 2015, we measured the size of a minimal Flutter app, bundled as an APK, to be approximately 8MB. For this simple app that used Material Design widgets, the core engine is approximately 5MB, the framework + app code is approximately 400kb, necessary Java code is 330k, and there is approximately 2.5MB of ICU data. We are working to get this smaller.

Where can I get support?

If you think you’ve encountered a bug, please file it in our issue tracker. We encourage you to use Stack Overflow for “HOWTO” type questions. For discussions, please join our mailing list at flutter-dev@googlegroups.com.

How do I get involved?

Flutter is open source, and we encourage you to contribute. You can start by simply filing issues for feature requests and bugs in our issue tracker. You should also join our mailing list at flutter-dev@googlegroups.com and let us know how you’re using Flutter and what you’d like to do with it. If you’re interested in contributing code, you can start by reading our Contributing guide.

Should I build my next production app with Flutter?

As of November 2015, Flutter is still being developed heavily and is not yet at 1.0. While lower levels of the system are changing less, we envision changing parts of the system based on early adopter feedback.

I heard Apple rejects apps built with third-party frameworks, is that true? Will Apple reject my Flutter app?

We can’t speak for Apple, but Apple’s policies have changed, and they have allowed apps built with systems like Flutter. Of course, Apple is in ultimately in charge of their ecosystem, but our goal is to continue to do everything we can to ensure Flutter apps can be deployed into Apple’s App Store.

What language is Flutter written in?

We looked at a lot of languages and runtimes, and ultimately adopted Dart for the framework and widgets. The underlying graphics framework and the Dart virtual machine are implemented in C/C++.

Why did Flutter choose to use Dart?

Dart gives us a scalable language and a feature set that supports simple scripts all the way up to full-featured apps. We wanted something that would be instantly familiar to JavaScript, Java, and C# developers. Dart’s robust core libraries meant that we didn’t need to write a lot of core library code.

We also wanted our apps to be extremely fast, and in our experience the Dart VM has very impressive performance. We also really liked the Dart VM’s other features like the Observatory (a real-time VM profiler, debugger, and introspection tool) and snapshots (a binary form of the app that’s quick to load).

Very important was the requirement to run fast on iOS. The Dart VM supports an ahead-of-time compilation mode, meaning we can compile Dart code to native code and ship a Flutter app to Apple’s App Store.

In short, we adopted Dart because it was the best language that we could find that we wanted to code in every day.

Can Flutter run any Dart code?

Flutter should be able to run most Dart code that does not import (transitively, or directly) dart:mirrors or dart:html.

Who works on Flutter?

Flutter is an open source project. Currently, the bulk of the development is done by engineers at Google. If you’re excited about Flutter, we encourage you to join the community and contribute to Flutter!