Hello Jon,
I had a similar problem with a different method (ReadFromUrl) where
Cocoa was supplying NULL for the outError parameter in some cases, and
it's not possible to convert null to an "out NSError" parameter in C#.
In the end I just didn't use the method from MonoMac and defined my own
like this:
[Export("readFromURL:ofType:error:")]
private bool ReadFromUrl2(NSUrl absoluteUrl, string typeName, IntPtr pOutError)
{
// Set this to an NSError object if an error occurs
NSError nsError;
// ...
// Write the error to the out parameter
if (pOutError != IntPtr.Zero)
{
if (nsError == null)
{
Marshal.WriteIntPtr(pOutError, IntPtr.Zero);
}
else
{
Marshal.WriteIntPtr(pOutError, nsError.Handle);
}
}
}
Maybe not the best way of solving it, but it worked for me!
Dan
On 25/04/2012 05:03, Jon Lipsky wrote:
Hi All,
I'm running into a strange problem that I though perhaps someone else
might have run into and might have a solution for.
If I were writing a document based application in Objective-C and
wanted to the user to be able to cancel the opening of a document, I
could do something like this (which I can confirm works fine):
- (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName
error:(NSError **)outError
{
// Loading code here...
*outError = [NSErrorerrorWithDomain:NSCocoaErrorDomain
code:NSUserCancelledError userInfo:nil];
returnNO;
}
The (what seems to me) obvious thing to do in MonoMac would be to
implement this:
public override bool ReadFromData (NSData data, string typeName, out
NSError outError)
{
// Loading code here...
outError = NSError.FromDomain(NSError.CocoaErrorDomain,1376);
return false;
}
However, when I do so, my app crashes with the following stack trace:
#0 0x9287dfd5 in __wait4 ()
#1 0x93be04ec in waitpid$UNIX2003 ()
#2 0x0009fe9b in mono_handle_native_sigsegv (signal=11,
ctx=0xbfffea5c) at mini-exceptions.c:2192
#3 0x00004f6e in mono_sigsegv_signal_handler (_dummy=10,
info=0xbfffea1c, context=0xbfffea5c) at mini.c:5917
#4 <signal handler called>
#5 0x9249cd44 in objc_msgSend ()
#6 0x991622cc in -[NSDocumentController(NSInternal)
_fixedFailureReasonFromError:] ()
#7 0x9916b5f4 in -[NSDocumentController
_willPresentOpeningError:forURL:] ()
#8 0x9916b197 in -[NSDocumentController
_openDocumentsWithContentsOfURLs:presentErrors:completionHandler:] ()
#9 0x9915f749 in -[NSDocumentController openDocument:] ()
(Rest of stack trace omitted)
Has anyone else run into this problem, and if so were you able to find
a solution/workaround?
Thanks,
Jon...
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