CLI Reference

swift4j-cli is the code generator that produces Kotlin and Java proxy classes from Swift source files. The generate-java-bridging SPM plugin invokes it automatically — use the CLI directly only when you need to integrate code generation into a custom build pipeline.

Usage

swift4j-cli [options] <swift-files...>

Pass one or more .swift source files. The tool parses them, finds all @jvm-annotated types, and generates proxy classes.

Options

Option	Required	Default	Description
--package <name>	Yes	—	Java package name for the generated classes
-o <dir> / --outdir <dir>	No	stdout	Directory to write generated files into
--java-version <version>	No	11	Java language compatibility level
--generate-android-viewmodels	No	off	Generate Android ViewModel wrappers for @Observable types

Examples

Generate to stdout (useful for inspection):

swift4j-cli --package com.example.mylib Sources/MyLib/Service.swift

Generate to a directory:

swift4j-cli --package com.example.mylib \
    -o generated/src/main/java \
    Sources/MyLib/Service.swift \
    Sources/MyLib/Models.swift

Generate with Android ViewModel support:

swift4j-cli --package com.example.mylib \
    --generate-android-viewmodels \
    -o generated/src/main/java \
    Sources/MyLib/*.swift

Package naming

The --package value becomes the Java/Kotlin package declaration in all generated files. The generated class for a Swift type Foo in package com.example.mylib is imported in Kotlin as:

import com.example.mylib.Foo

When using the SPM generate-java-bridging plugin, the package name is derived automatically from the target name (hyphens replaced with underscores). Pass --package only when invoking the CLI directly.