麻烦xamarin.ios/monotouch,mvvmcross和链接

Question

我有一个恼人的问题,如果我只在xamarin工作室使用链接SDK程序集我得到一个例外,如果我使用不链接异常没有发生.我已经将问题定位为我正在使用的第三方dll的一部分(api用于视频流服务).我相信链接器正在剥离这个dll使用的一些方法.是否可以跳过某些库的链接,是否可以从这个堆栈跟踪中查看哪些库.

    2013-05-08 14:40:54.688 AppsfabrikkenTouch[5662:907] mvx: Diagnostic:  18,23 Exception masked NullReferenceException: Object reference not set to an instance of an object
      at System.Delegate.Combine (System.Delegate a, System.Delegate b) [0x00018] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System/Delegate.cs:473 
  at Cirrious.MvvmCross.ViewModels.MvxNotifyPropertyChanged.add_PropertyChanged (System.ComponentModel.PropertyChangedEventHandler value) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Bindings.Source.MvxBasePropertyInfoSourceBinding..ctor (System.Object source, System.String propertyName) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Bindings.Source.MvxPropertyInfoSourceBinding..ctor (System.Object source, System.String propertyName) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Bindings.Source.Construction.MvxSourceBindingFactory.CreateBinding (System.Object source, IEnumerable`1 childPropertyNames) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Bindings.Source.Construction.MvxSourceBindingFactory.CreateBinding (System.Object source, System.String combinedPropertyName) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Binders.MvxFullBinding.CreateSourceBinding (System.Object source) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Binders.MvxFullBinding..ctor (Cirrious.MvvmCross.Binding.Interfaces.MvxBindingRequest bindingRequest) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Binders.MvxFromTextBinder.BindSingle (Cirrious.MvvmCross.Binding.Interfaces.MvxBindingRequest bindingRequest) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Binders.MvxFromTextBinder+<>c__DisplayClass1.<Bind>b__0 (Cirrious.MvvmCross.Binding.Interfaces.MvxBindingDescription description) [0x00000] in <filename unknown>:0 
  at System.Linq.Enumerable+<CreateSelectIterator>c__Iterator1D`2[Cirrious.MvvmCross.Binding.Interfaces.MvxBindingDescription,Cirrious.MvvmCross.Binding.Interfaces.IMvxUpdateableBinding].MoveNext () [0x00000] in <filename unknown>:0 
  at System.Collections.Generic.List`1[Cirrious.MvvmCross.Binding.Interfaces.IMvxUpdateableBinding].AddEnumerable (IEnumerable`1 enumerable) [0x00000] in <filename unknown>:0 
  at System.Collections.Generic.List`1[Cirrious.MvvmCross.Binding.Interfaces.IMvxUpdateableBinding].AddRange (IEnumerable`1 collection) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Touch.ExtensionMethods.MvxBindingTouchExtensions.AddBindings (IMvxBindingTouchView view, IEnumerable`1 bindings) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Touch.ExtensionMethods.MvxBindingTouchExtensions.AddBindings (IMvxBindingTouchView view, System.Object source, System.Object target, System.String bindingText) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Touch.ExtensionMethods.MvxBindingTouchExtensions.AddBindings (IMvxBindingTouchView view, System.Object source, IDictionary`2 bindingMap) [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Binding.Touch.ExtensionMethods.MvxBindingTouchExtensions.AddBindings (IMvxBindingTouchView view, IDictionary`2 bindingMap) [0x00000] in <filename unknown>:0 
  at CmsApp.Touch.TabTextView.ViewDidLoad () [0x00074] in /Volumes/2end HDD/Dropbox/AppProjects/Appsfabrikken/CmsApp.Touch/Views/UmbracoViews/TabTextView.cs:45 
  at MonoTouch.UIKit.UINavigationController.PushViewController (MonoTouch.UIKit.UIViewController viewController, Boolean animated) [0x00019] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UINavigationController.g.cs:178 
  at CmsApp.Touch.AppPhonePresenter.Show (IMvxTouchView view) [0x0007b] in /Volumes/2end HDD/Dropbox/AppProjects/Appsfabrikken/CmsApp.Touch/AppPhonePresenter.cs:62 
  at Cirrious.MvvmCross.Touch.Views.Presenters.MvxTouchViewPresenter.Show (Cirrious.MvvmCross.Views.MvxShowViewModelRequest request) [0x00000] in <filename unknown>:0 
  at CmsApp.Touch.AppPhonePresenter.Show (Cirrious.MvvmCross.Views.MvxShowViewModelRequest request) [0x00000] in /Volumes/2end HDD/Dropbox/AppProjects/Appsfabrikken/CmsApp.Touch/AppPhonePresenter.cs:37 
  at Cirrious.MvvmCross.Touch.Views.MvxTouchViewDispatcher+<>c__DisplayClass1.<RequestNavigate>b__0 () [0x00000] in <filename unknown>:0 
  at Cirrious.MvvmCross.Touch.Views.MvxTouchUIThreadDispatcher+<>c__DisplayClass1.<InvokeOrBeginInvoke>b__0 () [0x00000] in <filename unknown>:0 

任何帮助表示赞赏.

更新:正如stuart所建议的那样(感谢stuart)我添加了一个LinkerPleaseInclude文件,其中包含以下内容:但它仍然会出现异常.

class LinkerIncludePlease
    {
        private void DelegateCombine(Delegate a, Delegate b)
        {
            var d = Delegate.Combine(a,b);
        }

        private void DelegateCombine(params Delegate[] delegates)
        {
            var d = Delegate.Combine(delegates);
        }

        private void DelegateCombine()
        {
            var d = Delegate.Combine();
        }

    }

我的想法是它必须是与堆栈跟踪相关的东西

Exception masked NullReferenceException: Object reference not set to an instance of an object
          at System.Delegate.Combine (System.Delegate a, System.Delegate b) [0x00018] 

但它似乎没有做到这一点 - 任何指针找到被剥离的东西？

Answer 1

是否可以跳过某些库的链接

是.您可以使用该--linkskip=ASSEMBLY选项(在项目选项中的其他mtouch参数中)将问题(并且100%确定其来源)隔离到第三方.它也可以用作发布解决方法(但您最好找到一个更精确的解决方案,以便从链接器中获得全部好处).

例如,--linkskip=mscorlib会跳过mscorlib.dll(即没有文件扩展名)

是否有可能从这个堆栈跟踪中看到哪个？

不完全的.问题不在于System.Delegate.Combine.由于它在堆栈跟踪中命名,因此您知道它不会被链接器删除.

OTOH其中一个论点(代表)很可能被删除.如果它是使用反射创建的(因为链接器使用静态分析),那么(很可能)会发生这种情况.您可以使用堆栈跟踪来查看Combine调用中应该使用的内容(类型)并从那里向后工作,例如查找它是如何创建的.

一旦找到它,您将希望链接器保留它.您可以通过添加额外的,不需要的代码(如@Stuart建议)来实现.我自己的建议是:

• [Preserve]拥有源代码时使用属性;

• 当你没有源代码时,使用XML文件(和--xml=file);

Answer 2

当链接器执行其工作时，我无法找到丢失的内容。

然而，我发现在一次绑定期间，视频 api 正在执行同步 RestSharp 调用，这使得绑定等待完成，这似乎导致了问题。如果我更改了工作流程并启动了异步 Restsharp 调用，然后在完成后启动绑定，那么这一切都会发挥作用。

非常感谢您的帮助。