问题
I have the following property that I am binding:
@property (nonatomic, readwrite, retain) NSArray* activeTasks;
That I bind with the following code:
[Export("activeTasks", ArgumentSemantic.Retain)]
NSDictionary[] ActiveTasks { get; }
I use this property very often. Nevertheless, once every thousand of accesses, I get a SIGSEGV on get_activeTasks (the binding of the selector). I wonder what I am doing wrong and why this only happens very rarely instead of systematically.
at (wrapper managed-to-native) MonoTouch.ObjCRuntime.Messaging.void_objc_msgSend (intptr,intptr) <IL 0x00024, 0xffffffff>
at MonoTouch.Foundation.NSObject.InitializeObject (bool) [0x00062] in /Developer/MonoTouch/Source/monotouch/src/Foundation/NSObject.cs:136
at MonoTouch.Foundation.NSObject..ctor (intptr,bool) [0x0000d] in /Developer/MonoTouch/Source/monotouch/src/Foundation/NSObject.cs:62
at MonoTouch.Foundation.NSObject..ctor (intptr) <IL 0x00003, 0x0002b>
at MonoTouch.Foundation.NSDictionary..ctor (intptr) <IL 0x00002, 0x00027>
at MonoTouch.Foundation.NSMutableDictionary..ctor (intptr) <IL 0x00002, 0x00027>
at (wrapper runtime-invoke) <Module>.runtime_invoke_void__this___intptr (object,intptr,intptr,intptr) <IL 0x00054, 0xffffffff>
at (wrapper managed-to-native) System.Reflection.MonoCMethod.InternalInvoke (System.Reflection.MonoCMethod,object,object[],System.Exception&) <IL 0x00030, 0xffffffff>
at System.Reflection.MonoCMethod.Invoke (object,System.Reflection.BindingFlags,System.Reflection.Binder,object[],System.Globalization.CultureInfo) [0x00109] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:536
at System.Reflection.MonoCMethod.Invoke (System.Reflection.BindingFlags,System.Reflection.Binder,object[],System.Globalization.CultureInfo) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:551
at System.Activator.CreateInstance (System.Type,System.Reflection.BindingFlags,System.Reflection.Binder,object[],System.Globalization.CultureInfo,object[]) [0x00174] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System/Activator.cs:299
at System.Activator.CreateInstance (System.Type,object[],object[]) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System/Activator.cs:234
at System.Activator.CreateInstance (System.Type,object[]) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System/Activator.cs:229
at MonoTouch.ObjCRuntime.Runtime.ConstructNSObject (intptr,intptr) [0x0000d] in /Developer/MonoTouch/Source/monotouch/src/ObjCRuntime/Runtime.cs:210
at MonoTouch.ObjCRuntime.Runtime.GetNSObject (intptr) [0x0001f] in /Developer/MonoTouch/Source/monotouch/src/ObjCRuntime/Runtime.cs:259
at MonoTouch.Foundation.NSArray.ArrayFromHandle<T> (intptr) [0x0003a] in /Developer/MonoTouch/Source/monotouch/src/shared/Foundation/NSArray.cs:172
at TouchDBBinding.CouchServer.get_ActiveTasks () <IL 0x0001b, 0x00073>
EDIT:
Here is an update stack trace using the new Framework, I don't know if it could help out more:
Stacktrace:
at (wrapper managed-to-native) MonoTouch.Foundation.NSObject.monotouch_create_managed_ref (intptr,intptr,bool) <IL 0x0002d, 0xffffffff>
at MonoTouch.Foundation.NSObject.CreateManagedRef (bool) [0x00000] in /Developer/MonoTouch/Source/monotouch/src/Foundation/NSObject.cs:93
at MonoTouch.Foundation.NSObject.InitializeObject (bool) [0x000cc] in /Developer/MonoTouch/Source/monotouch/src/Foundation/NSObject.cs:88
at MonoTouch.Foundation.NSObject..ctor (intptr,bool) [0x0000d] in /Developer/MonoTouch/Source/monotouch/src/shared/Foundation/NSObject2.cs:85
at MonoTouch.Foundation.NSObject..ctor (intptr) <IL 0x00003, 0x0002b>
at MonoTouch.Foundation.NSDictionary..ctor (intptr) <IL 0x00002, 0x00027>
at MonoTouch.Foundation.NSMutableDictionary..ctor (intptr) <IL 0x00002, 0x00027>
at (wrapper runtime-invoke) <Module>.runtime_invoke_void__this___intptr (object,intptr,intptr,intptr) <IL 0x00054, 0xffffffff>
at (wrapper managed-to-native) System.Reflection.MonoCMethod.InternalInvoke (System.Reflection.MonoCMethod,object,object[],System.Exception&) <IL 0x00030, 0xffffffff>
at System.Reflection.MonoCMethod.Invoke (object,System.Reflection.BindingFlags,System.Reflection.Binder,object[],System.Globalization.CultureInfo) [0x00109] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:530
at System.Reflection.MonoCMethod.Invoke (System.Reflection.BindingFlags,System.Reflection.Binder,object[],System.Globalization.CultureInfo) [0x00000] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/MonoMethod.cs:545
at System.Reflection.ConstructorInfo.Invoke (object[]) [0x0000e] in /Developer/MonoTouch/Source/mono/mcs/class/corlib/System.Reflection/ConstructorInfo.cs:62
at MonoTouch.ObjCRuntime.Runtime.ConstructNSObject (intptr,intptr) [0x00051] in /Developer/MonoTouch/Source/monotouch/src/ObjCRuntime/Runtime.cs:269
at MonoTouch.ObjCRuntime.Runtime.GetNSObject (intptr) [0x0001f] in /Developer/MonoTouch/Source/monotouch/src/ObjCRuntime/Runtime.cs:328
at MonoTouch.Foundation.NSArray.ArrayFromHandle<T> (intptr) [0x00044] in /Developer/MonoTouch/Source/monotouch/src/shared/Foundation/NSArray.cs:188
at TouchDBBinding.CouchServer.get_ActiveTasks () <IL 0x0001b, 0x00073>
Is it possible that there is something in the inner workings of MonoTouch that can be a problem when an NSArray* with retain is bound to an NSDictionary[] and that this said property is null? Or is it possible that it is because it has null content?
Thanks, Paul
回答1:
The stack trace indicates that the crash happens when MonoTouch tries to retain one of the elements of the NSArray.
One possible reason is that the particular element has already been freed (or is otherwise corrupted). In particular it is not because the element is null (this case is handled differently).
来源：https://stackoverflow.com/questions/15957609/occasional-sigsegv-in-nsarray-binding