Flutter is a new cross platform app development framework from Google that allows apps to be created for both Android (KitKat or later) and iOS (iOS 5 or later). It’s still being developed, primarily by engineers at Google.
Flutter is a high performance (60fps) 2D rendering engine with framework and widgets on top. There are also Material Design widgets. It’s all open source.
Internally, Flutter is a mix of C, C++, Dart and Skia (the 2D rendering engine). On Android, there a Dart VM that isn’t an interpreter. Instead, the Dart VM generates JIT-compiled optimized native code. On iOS the code is compiled with LLVM and Dart code is AOT-compiled into native code. On either platform you can call native services via IPC.
Flutter isn’t suitable for production apps just yet and you can’t yet produce installable apps that easily. On the plus side I can see it will be enable us to produce high performance, cross platform apps with much less effort and cost. However, I have some reservations.
The first is that the widgets don’t use the respective system’s underlying widgets. There are Material Design widgets but who is going to want these on iOS? iOS look and feel widgets are needed. Even if these were available, it will create ‘look and feel’ problems when Apple and Google update the system widgets in the future. Also, I can’t see how Flutter widgets would ever provide for all the theme/style customisations provided by the native platforms.
Of course, we have been here during Nokia’s ownership of Qt. Providing for respective platform UIs, especially over time, is a monumental task. Getting developers to learn a new language also requires some sort of motivation. Apple is managing it with Swift but people are coming from the much more unfriendly Objective-C. Another unknown is the Google internal politics of where this fits into existing Android dev tools. Again, internal politics helped to kill Nokia Qt. However, the wildcard is Oracle that could tip things the other way. Much longer term, there’s a (small?) chance Oracle’s continual battles over Java IP could tip Google into using an alternative.
Finally, Flutter isn’t the only cross-platform framework trying to use Dart. Fletch is also based on Dart.