The tool displays a high level summary of the size breakdown
in the terminal, and leaves a *-code-size-analysis_*.json file for more
detailed analysis in DevTools.

In addition to analyzing a single build, two builds can also be diffed by
loading two *-code-size-analysis_*.json files into DevTools. See
DevTools documentation for details.

Through the summary, you can get a quick idea of the size usage per category
(such as asset, native code, Flutter libraries, etc). The compiled Dart
native library is further broken down by package for quick analysis.

Warning:
  This tool on iOS creates a .app rather than an IPA. Use this tool to
  evaluate the relative size of the .app’s content. To get
  a closer estimate of the download size, reference the
  Estimating total size section above.

Deeper analysis in DevTools