How to call C lang function by SwiftUI

It’s a simple example of the C function with iOS.

Note: This example uses Xcode(Version 12.4) and Target for iOS 14.4

1. Create a new SwiftUI project with Xcode.
In the item “Life Cycle: ”, it doesn’t matter whether “SwiftUI App” or “UIKit App Delegate”.

2. Create the C file in the project.

File > New > File…

3. Check the checkbox of “Also create a header file”

When Input FILENAME, please check the checkbox of “Also create a header file”.

4. Select the “Create Bridging Header” button

5. Then we can get the new 3 files

After the above manipulation, we can get these 3 files automatically by Xcode.

• C Header File
• C File
• Bridging-Header File

6. Write some functions in the “C File”.

#include "ClangTest.h"
void testFunc() {
    printf("Hello, World!\n");
}

7. Write Function prototype in “C Header File”

#ifndef ClangTest_h
#define ClangTest_h
#include <stdio.h>
void testFunc();
#endif /* ClangTest_h */

8. Write #import “FILENAME.h” in “Bridging-Header File”

#import "ClangTest.h"

After these above manipulations, the C function “testFunc()” can be called in the SwiftUI project.

9. Let’s call the C function in SwiftUI with ButtonView in ContentView.swift

10. Then Run the iOS Simulator

The C Function will run.