Open Radar

 
Summary:

Steps to Reproduce:
- git clone https://github.com/apontious/reignOfError.git
- Open iOS project "Reign of Error" in latest release Xcode, Xcode 4.3.3, on latest release version of OS, which is 10.7.4 Lion
- Build and run in Simulator

Expected Results:
- Application runs fine.

Actual Results:
- Application crashes because NSError returned from ErrorDocument subclass of UIDocument in loadFromContents:ofType:error: appears to be getting released in the frameworks, then used.

Here's what I get from Instruments (I've added spaces to make the columns line up):

#	Category	Event Type	RefCt	Timestamp	Size	Responsible Library	Responsible Caller
0	NSError	Malloc	       1	        00:01.592.995	32	Foundation	        +[NSError errorWithDomain:code:userInfo:]
1	NSError	Autorelease	<null>	00:01.593.005	0	Foundation	        +[NSError errorWithDomain:code:userInfo:]
2	NSError	Retain	       2	        00:01.593.009	0	Reign of Error	        -[ErrorDocument loadFromContents:ofType:error:]
3	NSError	Autorelease	<null>	00:01.593.016	0	Reign of Error	        -[ErrorDocument loadFromContents:ofType:error:]
4	NSError	Release	      1         	00:01.593.023	0	GraphicsServices	GSEventRunModal
5	NSError	Release	      0	                00:01.593.024	0	GraphicsServices	GSEventRunModal
6	NSError	Zombie	      -1	        00:01.593.601	0	libsystem_c.dylib	start_wqthread

I may just be using the APIs wrong, but I thought you could just set an NSError** parameter to a newly-created NSError instance, and it would be retained/autoreleased to have a lifespan long enough for all its clients to use.

The only way to make it stick around long enough is if I keep my own strong reference around. There's a commented-out line in ErrorDocument which does just that, and it keeps it from crashing. But that seems like an unnecessary workaround.

Regression:
- I haven't tried this before, so I don't know if it's a regression from anything.