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Takuya Matsuyama

Posted on Sep 29, 2022

How to specify pre-processor flags to the JSI-based React Native libraries

#reactnative #ios #android #sqlite

Hi, it's Takuya.
I'm building a note-taking app called Inkdrop for mobile using React Native.

The app uses react-native-quick-sqlite, a fast wrapper of SQLite:

ospfranco / react-native-quick-sqlite

Fast SQLite for react-native.

New package op-sqlite. It is a lot faster and consumes much less memory.

View on GitHub

It embeds the latest version of SQLite in C/C++.
That means that you build SQLite from source in your RN project on Xcode and Android Studio (CMake).

It doesn't enable any compile-time options by default, and I needed to enable FTS5 for full-text search in my app.
It can be enabled by specifying a SQLITE_ENABLE_FTS5 pre-processor flag when compiling.

I've managed to enable FTS5 and I'd like to share how to do that in your project.
For Android, the library needs to make some changes. So, it'd be helpful for library maintainers who would support accepting custom build flags.

iOS

Fortunately, CocoaPods allows you to customize the pods project settings via Podfile:

https://guides.cocoapods.org/syntax/podfile.html

Add a post_install block to your <PROJECT_ROOT>/ios/Podfile like so:

post_install do |installer|
  installer.pods_project.targets.each do |target|
    if target.name == "react-native-quick-sqlite" then
      target.build_configurations.each do |config|
        config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= ['$(inherited)', '<SQLITE_FLAGS>']
      end
    end
  end
end

Replace the <SQLITE_FLAGS> part with flags you want to add.
For example, you could add SQLITE_ENABLE_FTS5=1 to GCC_PREPROCESSOR_DEFINITIONS to enable FTS5 in the iOS project.

Android

The native modules are compiled with CMake that reads CMakeLists.txt.

CMake supports adding flags with add_definitions command.

Add the following lines in the library's CMakeLists.txt:

add_definitions(
  ${SQLITE_FLAGS}
)

It specifies flags via the variable SQLITE_FLAGS, which needs to be specified in react-native-quick-sqlite/android/build.gradle like so:

def SQLITE_FLAGS = rootProject.properties['quickSqliteFlags']

android {
  defaultConfig {
    externalNativeBuild {
        cmake {
            arguments '-DANDROID_STL=c++_shared',
              "-DREACT_NATIVE_VERSION=${REACT_NATIVE_VERSION}",
              "-DNODE_MODULES_DIR=${nodeModules}",
              "-DSQLITE_FLAGS='${SQLITE_FLAGS ? SQLITE_FLAGS : ''}'"
        }
    }