怎样打包，可以参考官方文档
https://reactnative.cn/docs/signed-apk-android/
或者这篇文章也不错
https://www.cnblogs.com/shaoting/p/7117454.html
按照上面的打包又可能出现以下的错误
1、
......android/app/build/intermediates/res/merged/release/drawable-hdpi/node_modules_reactnavigationstack_dist_views_assets_backicon.png: error: uncompiled PNG file passed as argument. Must be compiled first into .flat file..
error: failed parsing overlays.
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:processReleaseResources'.
> Failed to process resources, see aapt output above for details.
* Try:
Run with **--stacktrace** option to get the stack trace. Run with **--info** or **--debug** option to get more log output. Run with **--scan** to get full insights.
* Get more help at [https://help.gradle.org](https://help.gradle.org)
解决的办法
原因及解决方法：在gradle.properties文件中添加以下行：android.enableAapt2 = false，它实质上使用旧的aapt来获取资源。
- 可能出现的错误
....../android/app/build/intermediates/res/merged/release/drawable-hdpi-v4/node_modules_reactnavigationstack_dist_views_assets_backicon.png: error: Duplicate file.
....../android/app/build/intermediates/res/merged/release/drawable-hdpi/node_modules_reactnavigationstack_dist_views_assets_backicon.png: Original is here. The version qualifier may be implied.
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:processReleaseResources'.
> Failed to process resources, see aapt output above for details.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
解决办法有两种：
第一种：
在这个目录下的文件node_modules/react-native/react.gradle :
在这方法里面 def currentBundleTask = tasks.create(...
在doFirst块之后） 添加以下代码到里面
doLast {
def moveFunc = { resSuffix ->
File originalDir = file("${resourcesDir}/drawable-${resSuffix}")
if (originalDir.exists()) {
File destDir = file("${resourcesDir}/drawable-${resSuffix}-v4")
ant.move(file: originalDir, tofile: destDir)
}
}
moveFunc.curry("ldpi").call()
moveFunc.curry("mdpi").call()
moveFunc.curry("hdpi").call()
moveFunc.curry("xhdpi").call()
moveFunc.curry("xxhdpi").call()
moveFunc.curry("xxxhdpi").call()
}
第二种解决办法：
用Android Studio打开android目录，找到res/drawable目录，把里面的图片文件都删掉（因为这些图片都是React Native自动生成的，所以删除即可）。再次重新执行gradlew assembleRelease命令就不会报错了。
