Experiment with a native iOS text input

[gnprice]

As described at #47, there are several issues in the Flutter tracker where people are unhappy with the Flutter text-input widget, particularly on iOS.

One solution we should explore is to use a native text input on iOS. (This is effectively what we already get in the React Native app.) There are two basic paths for how to do this:

• There's an existing plugin flutter_native_text_input some people have built for this.
• We could also build our own, using Flutter's general facilities for interoperating with platform features:
  • https://docs.flutter.dev/development/platform-integration/ios/platform-views
  • https://pub.dev/packages/pigeon

[gnprice]

About that existing plugin, one user writes (2023-01-10):

That plugin [] was sort of abandoned due to issues with platform views, especially in multiline mode and on the android side.

(A platform view is what makes it possible to take something like a native text input and put it in a Flutter widget.)

I don't know what the specific issues are, or whether they still exist. In general the highest-upvoted platform-views issues have been fixed:
https://github.com/flutter/flutter/issues?q=is%3Aissue+label%3A%22a%3A+platform-views%22+sort%3Areactions-%2B1-desc+is%3Aclosed
though there are plenty of open issues too:
https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22a%3A+platform-views%22+sort%3Areactions-%2B1-desc

I guess here's one particularly concerning issue:

• Platform Views are massively expensive and the docs and instrumentation don't highlight this enough. flutter/flutter#40108

Some of that documentation now exists:
https://docs.flutter.dev/platform-integration/android/platform-views#performance

[gnprice]

We'll stick with Flutter's own text input. We haven't heard anything from our own users about the sorts of issues described in #47; if we do, we can invest in getting them fixed upstream.