Support building Android and IOS

[Wuhy5]

Hi, I would like to ask how to support compilation for Android and iOS. If possible, what do I need to do?

[dginev]

We can start with identifying the compiler targets for those OS-es and adding them to the continuous integration tests in the repository. I am assuming a refresher on Rust platform-support will be useful, as well as picking a way to install the native libxml2 headers for each platform.

I don't develop for either platform, so feel encouraged to contribute the enhancements as PRs.

[Wuhy5]

Thanks for your answer, I will try it.
Currently I have no problem using GithubAction to cross compile IOS on Macos, but Android has problems.

[Wuhy5]

https://github.com/Wuhy5/rust-libxml
I tried it and it should be able to compile and generate staticlib successfully.
I hope my modification can help you. My personal level is limited and I have just come into contact with this knowledge.
For iOS, as long as libxml2 is installed on the MacOS system, cross-compilation to iOS is supported.

[dginev]

I guess we should consider your android-build.yml and ios-build.yml.

And the changes you enacted in build.rs to support that.

[Wuhy5]

The idea is that you need to build the corresponding cross-compiled libxml2 locally and set the corresponding environment variables (not using pkg-config to cross-compile, because I don't know why it doesn't work), and secondly, you need to use the clang provided by the Android NDK to use the clang, or bind the Android NDK's corresponding system libraries to the clang.

[Wuhy5]

I also tried compiling the custom_example.rs file in examples as an Android executable, which I successfully executed using an adb shell into the Android system.

[Wuhy5]

Prebuild I referenced the program https://github.com/djp952/prebuilt-libxml2