The correct way to mix Swift and C

Swift is a powerful programming language, while C is a classic and widely used programming language. In some cases, we may need to use C code in a Swift project to take advantage of specific features of the C language or an existing C code base. This article will introduce how to correctly mix Swift and C code in a Swift project.

1. Create a hybrid Swift project

First, we need to create a new Swift project or add C code to an existing Swift project. Make sure you have the project open in Xcode.

2. Create C language header file

To be able to use C functions and variables in Swift code, we need to create a C language header file. This header file will contain the declarations of the C functions and variables we want to use.

In the root directory of your project, create a new header file, eg MyCFile.h. In header files we can declare C functions and variables. Here is an example:

#ifndef MyCFile_h
#define MyCFile_h

int addTwoNumbers