[InputAccessoryView] Can't specify keyboard-conditional bottom padding

Environment

React Native Environment Info:
  System:
    OS: macOS High Sierra 10.13.5
    CPU: x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
    Memory: 25.07 MB / 16.00 GB
    Shell: 3.2.57 - /bin/bash
  Binaries:
    Node: 9.3.0 - ~/.nvm/versions/node/v9.3.0/bin/node
    Yarn: 1.6.0 - /usr/local/bin/yarn
    npm: 6.1.0 - ~/.nvm/versions/node/v9.3.0/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    iOS SDK:
      Platforms: iOS 11.4, macOS 10.13, tvOS 11.4, watchOS 4.3
    Android SDK:
      Build Tools: 23.0.1, 25.0.0, 25.0.1, 25.0.2, 25.0.3, 26.0.1, 26.0.2, 26.0.3, 27.0.3
      API Levels: 23, 25, 26
  IDEs:
    Android Studio: 3.1 AI-173.4819257
    Xcode: 9.4.1/9F2000 - /usr/bin/xcodebuild
  npmPackages:
    react: 16.4.1 => 16.4.1
    react-native: ^0.56.0 => 0.56.0

Description

If you have a bottom tab bar, you want the InputAccessoryView to appear above it when the keyboard is collapsed. However, when the keyboard is expanded, you want the InputAccessoryView to appear directly above the keyboard.

This sort of "conditional" bottom padding is currently impossible with InputAccessoryView. It seems that when the keyboard is expanded, the distance between the bottom of the screen and the InputAccessoryView is fixed. Attempting to change this distance with height, padding, or margin style properties does not seem possible.

Reproducible Demo

I've created a minimal repro here.

从链接的 TabsWithInputAccessoryView 最小复现开始，观察键盘收起和展开时 InputAccessoryView 的位置。根据该复现追踪 React Native 的 InputAccessoryView 实现，以确定底部间距在哪里被固定；完成的标准是：键盘收起时 accessory 可以位于标签栏上方，键盘展开时可以紧贴键盘上方。