Re: strange crash in NSAccessibility
Re: strange crash in NSAccessibility
- Subject: Re: strange crash in NSAccessibility
- From: James Maxwell <email@hidden>
- Date: Fri, 19 Feb 2010 11:17:29 -0800
okay, thanks Greg. Good to know that assistive devices isn't supposed to gate crash just any old cocoa party!
I'll look for the memory bug.
cheers,
J.
On 2010-02-19, at 10:53 AM, Greg Parker wrote:
> On Feb 19, 2010, at 10:41 AM, James Maxwell wrote:
>> I have a strange crash happening while trying load an open file window/sheet (NSOpenPanel).
>> I've got a simple AppController class, which is set as the Application's delegate. This is all there is to the controller, at this point:
>>
>> I actually have no idea why the NSAccessibility stuff is coming up, and the docs didn't shed much light for me. The bt is below.
>> It loads the sheet, then lists the files in the selected directory, then crashes. It works fine if I disable access for assistive devices on the system, but is there some legit way around this? Some exception I should be handling? This is the first time I've run into any accessibility stuff.
>>
>> #0 0x97c54a16 in -[NSException raise] ()
>> #1 0x931ac55c in NSAccessibilityAttributeValue ()
>> #2 0x933c443f in CopyAppKitUIElementAttributeValueNoCatch ()
>> #3 0x933c69d7 in CopyAttributeValue ()
>> #4 0x90461ad3 in _AXXMIGCopyAttributeValue ()
>> #5 0x9046bb96 in _XCopyAttributeValue ()
>> #6 0x9043dc39 in mshMIGPerform ()
>> #7 0x97b758db in __CFRunLoopRun ()
>> #8 0x97b73864 in CFRunLoopRunSpecific ()
>> #9 0x97b73691 in CFRunLoopRunInMode ()
>> #10 0x91a39f0c in RunCurrentEventLoopInMode ()
>> #11 0x91a39cc3 in ReceiveNextEventCommon ()
>> #12 0x91a39b48 in BlockUntilNextEventMatchingListInMode ()
>> #13 0x93160ac5 in _DPSNextEvent ()
>> #14 0x93160306 in -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] ()
>> #15 0x9312249f in -[NSApplication run] ()
>> #16 0x9311a535 in NSApplicationMain ()
>> #17 0x00002828 in main () at main.m:13
>
> This sort of backtrace is what happens when the assistive device machinery interrogates your process. If you don't write any accessibility code then assistive devices might not work well with your program, but it's not expected to crash.
>
> The first thing to do is to look in the console for an error message printed by that exception. My guess is that you have a memory error elsewhere, and the exception is "unrecognized selector" because your memory error mangled the accessibility data structures. If that's the case then the Zombie Instrument should help find the bug.
>
>
> --
> Greg Parker email@hidden Runtime Wrangler
>
>
James B Maxwell
Composer/Doctoral Student
School for the Contemporary Arts (SCA)
School for Interactive Arts + Technology (SIAT)
Simon Fraser University
email@hidden
email@hidden
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