在 C 中使用来自 Swift 的 Char 数组

Question

目前我有三个文件

main.swift

var dog = Dog()

dog.age = 12
dog.name = "H" // This is the non workable code

CTester.c

#include <stdio.h>

struct Dog {
    int age;
    char name[10];
} Dog;

和 C Test-Bridging-Header

#import "CTester.c"

我试图在 Swift 中使用 C 结构，但是，Char 数组在 Swift 中显示为 10 个 Int8 的数组。如何获取 Swift 字符串并将其分配给 char 数组？

Answer 1

所以，你可以像这样为你的Dog 写一些扩展：

斯威夫特 2

extension Dog {
    var Name: String {
        mutating get {
            return withUnsafePointer(&self.name) {namePtr in
                let charPtr = UnsafePointer<CChar>(namePtr)
                //Sorry, this code may crash here...
                return String(CString: charPtr, encoding: NSUTF8StringEncoding)!
            }
        }
        set {
            withUnsafeMutablePointer(&self.name) {namePtr in
                let charPtr = UnsafeMutablePointer<CChar>(namePtr)
                let size = sizeofValue(self.name)
                strncpy(charPtr, newValue, size - 1)
                charPtr[size - 1] = 0
            }
        }
    }
}

Swift 3（使用 Xcode 8 beta 4 测试）

extension Dog {
    var Name: String {
        mutating get {
            return withUnsafePointer(&self.name) {namePtr in
                let charPtr = UnsafePointer<CChar>(namePtr)
                //The result may contain the Unicode replacement character ("\u{FFFD}")
                return String(cString: charPtr)
            }
        }
        set {
            withUnsafeMutablePointer(&self.name) {namePtr in
                let charPtr = UnsafeMutablePointer<CChar>(namePtr)
                let size = sizeofValue(self.name)
                strncpy(charPtr, newValue, size - 1)
                charPtr[size - 1] = 0
            }
        }
    }
}

在 Martin R 的评论中看到the linked thread，可能还有一些改进的空间...... （特别是使用strlcpy 可以减少代码大小并提高安全性。请检查一下。）

但无论如何，它的工作原理是：

dog.Name = "H"
print(dog.Name) //->H

---

我发现 Name 的 getter 可能会使您的应用崩溃... “它有效”的限制是您只能存储 ASCII 字符。