最新测试版中的Swift C void *和void **指针（4）

In previous betas, I was able to pass a pointer to anything to C doing something like this

在以前的测试版中,我能够将指向任何东西的指针传递给C做类似的事情

var aString : NSString = "This is a string" // create an NSString
var anUnmanaged = Unmanaged.passUnretained(aString) // take an unmanaged pointer
var opaque : COpaquePointer = anUnmanaged.toOpaque() // convert it to a COpaquePointer
var mut : CMutablePointer = &opaque // this is a CMutablePointer
doSomething(mut) // pass the pointer to an helper function written in C

With the C function like this:

使用C函数是这样的:

void doSomething(void ** ptr)
{
   // do something with the pointer, change it and make it point to another nsstring for example
}

Now, (for sure in Beta4, maybe even in Beta3) the syntax translated from C to Swift has changed

现在,(肯定在Beta4中,甚至可能在Beta3中)从C转换为Swift的语法已经改变

Before, the doSomething function was expecting a CMutablePointer (that now has been removed from Swift) Now, it expects a:

之前,doSomething函数期待CMutablePointer(现在已从Swift中删除)现在,它期望:

UnsafePointer<UnsafePointer<()>>

() is a typealias to Void

()是Void的类型

So, syntactically talking is more clear. However, Now I can't understand how to take the void** pointer of any object like I was doing in previous betas.

所以,语法上的说话更清楚。但是,现在我无法理解如何获取任何对象的void **指针,就像我在之前的测试版中所做的那样。

Any suggestion?

3 个解决方案

#1

This worked for me:

这对我有用:

var str = "Hello, playground"
var p: UnsafePointer<Void> = unsafeAddressOf(str)

#2

Not sure if this is the correct answer, I hope that someone has a better method to do this. The main problem was that there is no direct conversion between a Swift Object and a Void UnsafePointer ( UnsafePointer<()> ) However I managed how to do it passing through a COpaquePointer

不确定这是否是正确的答案,我希望有人有更好的方法来做到这一点。主要问题是Swift对象和Void UnsafePointer(UnsafePointer <()>)之间没有直接转换但是我管理了如何通过COpaquePointer进行转换

    // since I can't go directly from NSMutableString to UnsafePointer<()> (which is UnsafePointer<Void>) i pass through a COpaquePointer
    var aString : NSMutableString = NSMutableString(string: "test") // create an NSString
    var anUnmanaged = Unmanaged.passUnretained(aString) // take an unmanaged pointer
    var opaque : COpaquePointer = anUnmanaged.toOpaque() // convert it to a COpaquePointer
    var anUnsafe : UnsafePointer<()> = UnsafePointer(opaque) // convert it to an UnsafePointer to Void ( () is a Typealias to Void) using the init(_ other: COpaquePointer) initializer

    doSomething(&anotherUnsafe)

#3

Can you try this:

你能试试这个:

let strPtr = unsafeBitCast(aString, UnsafePointer<Void>.self)
let strPtrPtr = unsafeBitCast(strPtr, UnsafePointer<Void>.self)

And then:

doSomething(strPtrPtr)

#1