在iOS上的Unity3d中使用IList时C#代码的无效行为

问题描述

我在用C#编写并为iPhone构建的Unity3D项目中发现了一个奇怪的行为.
有时 IList对象(实现IList接口的类型的对象)丢失有关元素类型的信息.在我的研究过程中，我发现发生在向IList进行类型转换的地方(例如，从 ArrayList 到 IList 的地方)并且 ToString()方法是叫.

I have found a strange behavior in my Unity3D project written in C# and built for iPhone.
Sometimes IList objects (objects of types which implement IList interface) lose information about elements types. During my research I figured out that it occurs when typecast to IList had a place (f.e. from ArrayList to IList) and ToString() method was called.

这是我从脚本的 Start()方法调用的一种简单测试方法.

Here is a simple test method I called from Start() method of my script.

public void IListToStringTest() {
  ConsolePrintln("---\nIListToStringTest");
  IList list = new ArrayList(); // <-- ARRAYLIST IS TYPECASTED TO ILIST

  list.Add(1);

  ConsolePrintln("Before \"listString = list.ToString()\"");

  ConsolePrintln("list[0] = " + list[0].ToString());
  ConsolePrintln("list[0].GetType().ToString() = " + list[0].GetType().ToString());
  ConsolePrintln("list[0] = " + list[0].ToString());
  ConsolePrintln("list[0].GetType().ToString() = " + list[0].GetType().ToString());
  ConsolePrintln("list[0] = " + list[0].ToString());
  ConsolePrintln("list[0].GetType().ToString() = " + list[0].GetType().ToString());

  string listString = list.ToString();

  ConsolePrintln("After \"listString = list.ToString()\"");

  ConsolePrintln("list[0] = " + list[0].ToString()); // <-- TYPE INFO IS ALREADY LOST
  ConsolePrintln("list[0].GetType().ToString() = " + list[0].GetType().ToString());
  ConsolePrintln("list[0] = " + list[0].ToString());
  ConsolePrintln("list[0].GetType().ToString() = " + list[0].GetType().ToString());
  ConsolePrintln("list[0] = " + list[0].ToString());
  ConsolePrintln("list[0].GetType().ToString() = " + list[0].GetType().ToString());

  ConsolePrintln("listString = " + listString);

  int intFromList = (int)list[0]; // <-- InvalidCastException IS THROWN HERE

  ConsolePrintln("intFromList = " + intFromList);
}

这是输出:

---
IListToStringTest
Before "listString = list.ToString()"
list[0] = 1
list[0].GetType().ToString() = System.Int32
list[0] = 1
list[0].GetType().ToString() = System.Int32
list[0] = 1
list[0].GetType().ToString() = System.Int32
After "listString = list.ToString()"
list[0] = System.Collections.ArrayList
list[0].GetType().ToString() = System.String
list[0] = System.Collections.ArrayList
list[0].GetType().ToString() = System.String
list[0] = System.Collections.ArrayList
list[0].GetType().ToString() = System.String
listString = System.Collections.ArrayList
System.InvalidCastException: Cannot cast from source type to destination type.
  at PPSSerializingTest.IListToStringTest () [0x001ba] in /Users/vlad/Projects/Unity/PPSSerializingTest/Assets/PPSSerializingTest.cs:171
  at PPSSerializingTest.Start () [0x00000] in /Users/vlad/Projects/Unity/PPSSerializingTest/Assets/PPSSerializingTest.cs:16

如您在调用 list.ToString()后所看到的，有关元素的信息丢失.

As you can see after list.ToString() was called information about element was lost.

请注意，并非每次都会复制此问题.从Xcode启动4次或更多次(不从Unity重新构建)之后，我在iPhone 4s(iOS 5.01)上重现了它.
我正在使用Unity 3.5.0b6，许可证类型:Unity，iPhone，Android.

Note, that this issue is not reproduced every time. I reproduced it on iPhone 4s (iOS 5.01) after 4 or more launches from Xcode (without rebuilding it from Unity).
I'm using Unity 3.5.0b6, license type: Unity, iPhone, Android.

有什么想法可能会发生这种情况吗?

Is there any idea why this may happen?

提前谢谢！

PS *我打开了另一个与此问题相关的主题:

PS* I have opened another thread about issue that can be related to this: C# List<object> to IList cast bug in Unity3d

推荐答案

基于我所看到的.这正是应该发生的行为.

Based on what I can see. This is exactly the behavior that should happen.

这会将集合IList转换为string，因此 liststring 的字符串值将是等于 System.Collections.IList 的string值. >如果我没记错的话.

This converts the collection which is an IList to a string so the string value of liststring would be string value equal to System.Collections.IList if I am not mistaken.

您基本上是在那一行上执行Type.ToString().至于ArrayList中的类型似乎正在改变的原因，老实说我无法解释，我怀疑发生了一些不正常的事情.

You are basically doing Type.ToString() on that line. As to the reason it appears the type in the ArrayList is changing, I honestly cannot explain that, I suspect something non-sinister is going on.

很容易成为

这至少会将liststring的值设置为ArrayList 列表

That would at least set the value of liststring to the first element of the ArrayList list

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