如何在 Xcode 11 package 管理器中处理 C 文件？

Question

I have a C-function, which I call in a Swift wrapper function. Now, I want to create a Swift-package with this Swift wrapper function. However, I am doing something wrong.

Here is the C-function which adds 2 double values.

//  addDoubles.c
#include <math.h>
#include "addDoubles.h"

double addDoubleWithC(double val1, double val2) {
    return val1 + val2;
}

Here is the Swift file with a wrapping function:

//  WrappedCFunctions.swift
import Foundation
public struct WrappedCFunctions {    
public static func addDoubles(val1:Double, val2:Double) -> Double{
    let resulFromCFunction = addDoubleWithC(val1, val2)
return resulFromCFunction
}
}

In the viewController I am using this function:

import UIKit

class ViewController: UIViewController {
@IBOutlet weak var textLabel: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()
    let val1 = 1.11
    let val2 = 2.22
    let result = WrappedCFunctions.addDoubles(val1: val1, val2: val2) 
    let txt = String(val1) + " + " + String(val2) + " = " + String(result)
    textLabel.text = txt
}
}

The project structure is the following:

This app works correctly, as expected.

In the next step I created with File-> New-> Swift Packe a package with name Math. Then I moved the file WrappedCFunctions.swift from the AddDoubles Folder into the CMath/Source/CMath folder of the package. In the next step I included the package into the project. This leads to the following structure:

Last but not least I added an Import CMath statement in ViewController.swift and built the project.

However, the package is not recognised.

How to fix this problem?

Answer 1

Without seeing your Package.swift file it is impossible to know if you package is setup correctly. Looking at the pictures you did post the best guess I have is that it is not configured properly.

The reason I am guessing this is that you only have 1 directory in your Sources/ when you will need 2 targets (usually with SwiftPM you have 1 directory per target and I don't see any.c files in the package). The C code will need to be a target that the Swift target depends on. Then you have a product that depends on the Swift target. That product is what you will link and import in Xcode.

If you look at this repo I have, I use both C and Swift so you can see how I have setup the Package.swift to build the 2 targets.