问题描述
A 有这样的结构(在 mongodb c 驱动的 bson.h 中定义):
A have a structure like this (defined in bson.h of mongodb c driver):
typedef struct
{
uint32_t domain;
uint32_t code;
char message[504];
} bson_error_t;
在 Swift 中，我有一个指向这个结构的指针，如下所示:
In Swift I have a pointer to this structure like this:
err: UnsafePointer<bson_error_t> = ...
现在无论我做什么，我都无法将 message[504] (Swift 将其视为 (Int8, Int8, Int8, ...504 次) 的元组)转换为 char* 在 String.fromCString() 中使用它.甚至有可能在 Swift 中做到这一点吗?作为临时解决方案，我在一个单独的 .c 文件中创建了一个辅助 C 函数，该文件采用 err *bson_error_t 并返回 char*，但这是奇怪的是Swift 自己做不到.
Now whatever I do I cannot convert message[504] (which Swift sees as a tuple of (Int8, Int8, Int8, ...504 times)) to char* to use it in String.fromCString().
Is it even possible to do that in Swift? As a temporary solution I created a helper C function in a separate .c file which takes err *bson_error_t and returns char*, but this is weird if
Swift cannot do it by itself.
推荐答案
这里是我的建议(类似于 rintaro 的方法，可能稍微简单一些):
Here my suggestion (similar to rintaro's approach, perhaps slightly simpler):
var err: UnsafeMutablePointer<bson_error_t> = ...
var msg = err.memory.message
let msgString = withUnsafePointer(&msg) { String.fromCString(UnsafePointer($0)) }
println(msgString)
这篇关于在 Swift 中获取指向 C 字符数组的指针的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！