swift - AutoreleasingUnsafeMutablePointer 崩溃 - 编译器中的错误？

Question

我正在慢慢地将我的代码库迁移到 Swift 并遇到了一个奇怪的崩溃，我正在填充一个 AutoreleasingUnsafeMutablePointer<String?>使用非零字符串。这是一些按比例缩小的代码:

extension String {
    func getRegexVariableNamed(name: String, forRegexString regexString: String) -> String? {
        /** ... **/
        return "TO BE IMPLEMENTED".lowercaseString // Using lowercase to prevent the compiler from inlining
    }
}

class XYZ {
    func extractInformation(info1: AutoreleasingUnsafeMutablePointer<String?>, info2: AutoreleasingUnsafeMutablePointer<String?>, info3: AutoreleasingUnsafeMutablePointer<String?>, info4: AutoreleasingUnsafeMutablePointer<String?>, fromSource source: String) -> Bool {
        guard let vp = source.getRegexVariableNamed("ID", forRegexString: "vp=(?P<ID>\\d+)") else {
            return false
        }

        info4.memory = vp
        info1.memory = "ABC"
        info2.memory = "DEF"
        info3.memory = "GHI" + vp
        return true
    }
}

// Code in playground
let obj = XYZ()

let info1 = AutoreleasingUnsafeMutablePointer<String?>()
let info2 = AutoreleasingUnsafeMutablePointer<String?>()
let info3 = AutoreleasingUnsafeMutablePointer<String?>()
let info4 = AutoreleasingUnsafeMutablePointer<String?>()
if !obj.extractInformation(info1, info2: info2, info3: info3, info4: info4, fromSource: "") {
    print("NO")
}else{
    print("YES")
}

应用程序(同样适用于 playground)崩溃并显示 error: Playground execution aborted: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).

此异常发生在将字符串设置为 AutoreleasingUnsafeMutablePointer 时在方法中 extractInformation(...) .

在将此作为错误报告给 Apple 之前，我想检查一下我是否没有做错什么。

顺便说一句，我在 OS X 10.10.5 上使用最新的 Xcode 7 beta (6)。

P.S.:我知道更 Swift 的方法是制作一个返回结构的方法，而不是使用这些自动释放指针，但如前所述，我正在慢慢地从 ObjC 转移，所以我需要它(现在)到向后兼容。

Answer 1

使用 Xcode 7.0.1，我可以使您的代码正常工作，并进行一些更改。

首先，在Using Swift with Cocoa and Objective-C (Swift 2)指南(“自动释放指针”一章)，它说声明为采用 AutoreleasingUnsafeMutablePointer<Type> 的函数可以接受 inout同样的表达 Type .

因此，代码可以更改如下:

let info1: String?
let info2: String?
let info3: String?
let info4: String?
if !obj.extractInformation(&info1, info2: &info2, info3: &info3, info4: &info4, fromSource: "") {
    print("NO")
}else{
    print("YES")
}

但是，还是不行。

但是，在同一页中，它表示 AutoreleasingUnsafeMutablePointer<Type>适用于类 类型映射。我不知道这是否是它不起作用的原因，很难猜测后面发生了什么，但如果你更换 String与 NSString , 你会得到一个结果。

extension String {
    func getRegexVariableNamed(name: String, forRegexString regexString: String) -> String? {
        /** ... **/
        return "TO BE IMPLEMENTED".lowercaseString // Using lowercase to prevent the compiler from inlining
    }
}

class XYZ {
    func extractInformation(info1: AutoreleasingUnsafeMutablePointer<NSString?>,
                            info2: AutoreleasingUnsafeMutablePointer<NSString?>,
                            info3: AutoreleasingUnsafeMutablePointer<NSString?>,
                            info4: AutoreleasingUnsafeMutablePointer<NSString?>,
                            fromSource source: String) -> Bool {
        guard let vp = source.getRegexVariableNamed("ID", forRegexString: "vp=(?P<ID>\\d+)") else {
            return false
        }

        info4.memory = vp
        info1.memory = "ABC"
        info2.memory = "DEF"
        info3.memory = "GHI" + vp
        return true
    }
}

// Code in playground
let obj = XYZ()

var info1: NSString?
var info2: NSString?
var info3: NSString?
var info4: NSString?
if !obj.extractInformation(&info1, info2: &info2, info3: &info3, info4: &info4, fromSource: "") {
    print("NO")
}else{
    print("YES")
    info1                // "ABC"
    info2                // "DEF"
    info3                // "GHIto be implemented"
    info4                // "to be implemented"
}