当我使用Firebase Unity和Unity 5.6 for iOS时，我遇到了很多这样的错误。有人可以帮忙吗？
TypeLoadException: Could not load type 'UnityEditor.iOS.Xcode.PBXProject' from assembly 'Google.IOSResolver'.
Google.IOSResolver..cctor ()
Rethrow as TypeInitializationException: An exception was thrown by the type initializer for Google.IOSResolver
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
Google.VersionHandler.InvokeMethod (System.Type type, System.Object objectInstance, System.String methodName, System.Object[] args, System.Collections.Generic.Dictionary`2 namedArgs)
Google.VersionHandler.InvokeStaticMethod (System.Type type, System.String methodName, System.Object[] args, System.Collections.Generic.Dictionary`2 namedArgs)
FirebaseAnalyticsDeps.SetupDeps () (at Assets/Firebase/Editor/AnalyticsDeps.cs:60)
FirebaseAnalyticsDeps..cctor () (at Assets/Firebase/Editor/AnalyticsDeps.cs:23)
Rethrow as TypeInitializationException: An exception was thrown by the type initializer for FirebaseAnalyticsDeps
System.Runtime.CompilerServices.RuntimeHelpers.RunClassConstructor (RuntimeTypeHandle type) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Runtime.CompilerServices/RuntimeHelpers.cs:101)
UnityEditor.EditorAssemblies.ProcessEditorInitializeOnLoad (System.Type type) (at C:/buildslave/unity/build/Editor/Mono/EditorAssemblies.cs:136)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.AssetPostprocessingInternal.PostprocessAllAssets (System.String[] importedAssets, System.String[] addedAssets, System.String[] deletedAssets, System.String[] movedAssets, System.String[] movedFromPathAssets) (at C:/buildslave/unity/build/Editor/Mono/AssetPostprocessor.cs:27)