Calling a C header from Swift (example)

I could not find a simple example of Swift code calling a C header. So I made one.

Usage:

swift build
.build/debug/SomeSwift

or

swift build --configuration release
.build/release/SomeSwift

Explanation:

• Each subdirectory in "Sources" is effectively a subpackage.
• Create a package with your C code in it (Sources/SomeC).
• Create your Swift package (Sources/SomeSwift).
• Then establish a dependency in your Package.swift file : targets: [Target(name: "Bitset", dependencies: ["SwiftBitsetC"]),].
• In your C package, add an include directory with your header file. If you have C source code, put it directly in your C code package directory (Sources/SomeC). You need at least one source file (somec.c).
• In your Swift code, just do import SomeC and then you can call the C function as in SomeC.sayHello().
• Offcial apple document about this topic: https://www.swift.org/documentation/articles/wrapping-c-cpp-library-in-swift.html

That's it!

For Xcode users (Mac only)

$ swift package generate-xcodeproj
generated: ./SwiftCallingCHeader.xcodeproj
$ open ./SwiftCallingCHeader.xcodeproj