当桥接到 NSError 实例时，代码如何归因于 Error 实例？

如何解决当桥接到 NSError 实例时，代码如何归因于 Error 实例？

我想知道如何将整数错误代码归因于 Error 的实例，因为它们被桥接到 NSError。

考虑以下代码：

import Foundation

enum CustomError: Error {
    case john(guitar: String)
    case paul(bass: String)
    case george(guitar: String)
    case ringo(drums: String)
    case didDetectSomething
    case didReceiveSomething
    case undecodableDate(dateAsstring: String)
    case unexpectedSomething(type: String)
    case nildeviceidentifier
}

let errors: [CustomError] = [
    .ringo(drums: "Ludwig"),.paul(bass: "Rickenbacker"),.george(guitar: "Fender"),.john(guitar: "Gibson"),.undecodableDate(dateAsstring: "String"),.didDetectSomething
]

errors.forEach { error in
    print(error)
    print(error.localizedDescription)
    let nsError = error as NSError
    print("code: \(nsError.code)")
}

它会输出：

ringo(drums: "Ludwig")
The operation Couldn’t be completed. (__lldb_expr_82.CustomError error 3.)
code: 3
paul(bass: "Rickenbacker")
The operation Couldn’t be completed. (__lldb_expr_82.CustomError error 1.)
code: 1
george(guitar: "Fender")
The operation Couldn’t be completed. (__lldb_expr_82.CustomError error 2.)
code: 2
john(guitar: "Gibson")
The operation Couldn’t be completed. (__lldb_expr_82.CustomError error 0.)
code: 0
undecodableDate(dateAsstring: "String")
The operation Couldn’t be completed. (__lldb_expr_82.CustomError error 4.)
code: 4
didDetectSomething
The operation Couldn’t be completed. (__lldb_expr_82.CustomError error 6.)
code: 6

似乎声明的顺序首先起作用（John 是 0，Paul 是 1 等），但随后 undecodableDate 的代码为 4，并在 didDetectSomething 之后声明了代码6.

所以我的问题是：

• 是否有任何有关此过程的文档？
• 它是随机的还是确定性的？ （更具体地说，无论编译或运行时配置如何，一段给定的代码是否总是最终将相同的代码归因于相同的错误？）