Implementation Steps

A bridging header is a special file in Xcode that allows Swift code to access functions written in languages that expose a C-compatible interface.

Although Go is not a C-based language, Go’s cgo toolchain can export Go functions using the C ABI, which makes them visible to Swift when included through a bridging header.

When you include a .h header file generated by Go (libfibonacci.h) inside your bridging header, Swift automatically imports those C-ABI functions and allows you to call your Go code as if it were native Swift.

This is essential when integrating Go static libraries (.a) into a Swift macOS application, because Swift cannot directly interpret Go types or symbols. The bridging header acts as the glue layer that exposes Go’s exported functions to the Swift compiler.

Why Bridging Headers Are Needed (Context)

When you compile Go code using:

go build -buildmode=c-archive -o libfibonacci.a .

Go produces two files:

• libfibonacci.a → a static archive containing compiled Go code
• libfibonacci.h → a generated C header describing the exported Go functions

Swift cannot access these functions by default. It doesn’t automatically scan .h files within the project.

To expose the Go functions to Swift, you create a bridging header such as:

GoWrapperMacApp-Bridging-Header.h

Inside it, you add:

#include "libfibonacci.h"

This tells Swift: