Xamarin.Mac: 创建本机实例 class 时出错 "the native class hasn't been loaded"，无法 dlopen

Question

我正在尝试让一个非常简单的测试框架在 MonoMac 中工作/Xamarin.Mac。这是一个只有一种方法的 32 位框架，"run" 就是 returns NSString @"OK"。当我导入 dll 并创建 class 的实例时，它会在运行时抛出以下错误：

Could not create an native instance of the type 'OPN200x.SimpleClass': the native class hasn't been loaded.
It is possible to ignore this condition by setting MonoMac.ObjCRuntime.Class.ThrowOnInitFailure to false.

我已经用 lipo 仔细检查过，二进制文件确实是 32 位的。
我已经尝试将运行这个框架导入到常规 Xcode 项目中它工作正常。
我刚刚在我的 MonoMac 项目中导入了一个 .dylib 进行测试，我可以打开它。
.framework 中的文件不会 dlopen。

这些是Main.cs的内容：

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using OPN200x;
using System.IO;
using MonoMac.Foundation;
using MonoMac.AppKit;
using MonoMac.ObjCRuntime;

namespace MacTest
{
    class MainClass
    {

        static void Main (string[] args)
        {
            var absolutePath = "/Users/UserName/Code/Xamarin/MacTest/MacTest/Frameworks/Simple.framework/Versions/A/Simple";
            if (!File.Exists (absolutePath)) {
                Console.Error.WriteLine ("File not found");
            } else {
                Console.WriteLine ("File Found");
            }

            var absolutePath2 = "/Users/UserName/Code/Xamarin/MacTest/MacTest/bin/Debug/MacTest.app/Contents/MonoBundle/libopn_driver.dylib";
            if (!File.Exists (absolutePath2)) {
                Console.Error.WriteLine ("File not found");
            } else {
                Console.WriteLine ("File Found");
            }

            var absolutePath3 = "/Users/UserName/Code/Xamarin/MacTest/MacTest/bin/Debug/MacTest.app/Contents/MonoBundle/Simple.framework/Versions/A/Simple";
            if (!File.Exists (absolutePath3)) {
                Console.Error.WriteLine ("File not found");
            } else {
                Console.WriteLine ("File Found");
            }

            if (Dlfcn.dlopen ("/Users/UserName/Code/Xamarin/MacTest/MacTest/bin/Debug/MacTest.app/Contents/MonoBundle/libopn_driver.dylib", 0) == IntPtr.Zero) {
                Console.Error.WriteLine("Unable to load libopn_driver.dylib"); // Does not get logged
            }

            Console.Error.WriteLine (System.Reflection.Assembly.GetExecutingAssembly ().Location);
            if (Dlfcn.dlopen("Simple.framework/Versions/A/Simple", 0) == IntPtr.Zero) 
            {
                Console.Error.WriteLine("Unable to load the dynamic library."); // Gets logged
            }

            if (Dlfcn.dlopen("/Users/UserName/Code/Xamarin/MacTest/MacTest/bin/Debug/MacTest.app/Contents/MonoBundle/Simple.framework/Versions/A/Simple", 2) == IntPtr.Zero) 
            {
                Console.Error.WriteLine("Unable to load the dynamic library."); // Gets logged
            }



            if (Dlfcn.dlopen("/Users/UserName/Code/Xamarin/MacTest/MacTest/Frameworks/Simple.framework/Versions/A/Simple", 2) == IntPtr.Zero) 
            {
                Console.Error.WriteLine("Unable to load the dynamic library."); // Gets logged
            }

            if (Dlfcn.dlopen("/Users/UserName/Code/Xamarin/MacTest/MacTest/Frameworks/Simple.framework/Simple", 2) == IntPtr.Zero) 
            {
                Console.Error.WriteLine("Unable to load the dynamic library."); // Gets logged
            }

            var simple = new SimpleClass (); // This line crashes
            var result = simple.Run;
            Console.WriteLine (result);

            NSApplication.Init ();
            NSApplication.Main (args);
        }
    }
}

它总能找到我检查的文件，但仅限于 dlopen，并且在使用 Simple 框架而不是 libopn_driver.dylib

时总是失败

Simple.dll 是用 sharpie 和 bmac 创建的，我认为最后一切顺利，但这是对它的描述：Converting custom native MacOS X library to dll using MonoMac

进一步调查

我在每个无法加载程序集的地方添加了以下日志：

Console.Error.WriteLine (Dlfcn.dlerror ());

这在每个地方都给我大致相同的错误：

    dlopen(/Users/UserName/Code/Xamarin/MacTest/MacTest/bin/Debug/MacTest.app/Contents/MonoBundle/Simple.framework/Versions/A/Simple, 2): no suitable image found.  Did find:
    /Users/UserName/Code/Xamarin/MacTest/MacTest/Frameworks/Simple.framework/Versions/A/Simple: unknown file type, first eight bytes: 0x21 0x3C 0x61 0x72 0x63 0x68 0x3E 0x0A
    /Users/UserName/Code/Xamarin/MacTest/MacTest/bin/Debug/MacTest.app/Contents/MonoBundle/Simple.framework/Versions/A/Simple: unknown file type, first eight bytes: 0x21 0x3C 0x61 0x72 0x63 0x68 0x3E 0x0A

我认为这意味着图像在某种程度上不兼容，但我不知道具体原因。我用文件测试过：

file Simple.Framework/Versions/A/Simple
Simple.Framework/Versions/A/Simple: current ar archive random library

和脂肪：

lipo Simple.Framework/Versions/A/Simple -info
input file Simple.Framework/Versions/A/Simple is not a fat file
Non-fat file: Simple.Framework/Versions/A/Simple is architecture: i386

乍一看这对我来说似乎没问题，生成的应用程序也是如此：

file MacTest
MacTest: Mach-O executable i386

MacOS Lucas$ lipo MacTest -i
Non-fat file: MacTest is architecture: i386

Answer 1

确保将框架设置为动态库：

现在文件的输出为：

file Simple.Framework/Versions/A/Simple
Simple.Framework/Versions/A/Simple: Mach-O dynamically linked shared library i386

Xamarin.Mac: 创建本机实例 class 时出错 "the native class hasn't been loaded"，无法 dlopen

Xamarin.Mac: Error "the native class hasn't been loaded" when creating instance of native class, cannot dlopen

c#

xcode

monomac

dlopen

xamarin.mac

进一步调查