Crash when releasing NSDictionary

[unplug]

I created a NSDictionary through dictionaryWithContentsOfFile message in initWithStyle of my controller which is a subclass of UITableViewController. This NSDictionary is then assigned to an instance variable, mydictionary, and released.

In the dealloc, I have:
[self.mydictionary release]
and the program crash in this line. I have no idea why this is happening.

Can someone shed some lights here? Thanks.
Martin

[kohjingyu]

Did you release your dictionary somewhere else?

Usually adding

[self.mydictionary release];
self.mydictionary = nil;

should fix it, I think.

[BrianSlick]

Don't send release messages to properties. If you want to clear out a property, do this:

[self setMyProperty:nil];

In dealloc, send the release message directly to the instance variable.

[myInstanceVariable release], myInstanceVariable = nil;

[sakrist]

set release only if your nsdictionary alloc or retain

?????????? ??????? ? Objective-c ??? iPhone - Notes of a Developer
Cocoa Touch: Memory management on the iphone

[unplug]

Originally Posted by sakrist

set release only if your nsdictionary alloc or retain

?????????? ??????? ? Objective-c ??? iPhone - Notes of a Developer
Cocoa Touch: Memory management on the iphone

When I dig deeper, I found the following codes have problem.

	NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"mylist" ofType:@"plist"];
	NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:plistPath];
	self.locationList = [dict valueForKey:@"location"];
	[dict release];

This is in the viewDidLoad() of a UITableViewController, and this UITableViewController is created when a button is clicked.

The problem is it did not crash every time the button was clicked. The first time is always ok, but the 2nd or 3rd time when that button was clicked, it crashed.

[unplug]

[myInstanceVariable release], myInstanceVariable = nil;

Do I have to use both, or just one? I think they are the same, right?

[BrianSlick]

	NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"mylist" ofType:@"plist"];
	NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:plistPath];
	self.locationList = [dict valueForKey:@"location"];
	[dict release];

You did not alloc, copy, new, or retain dict, so don't release it.

Originally Posted by unplug

[myInstanceVariable release], myInstanceVariable = nil;

Do I have to use both, or just one? I think they are the same, right?

You don't have to use both, and it probably doesn't matter in dealloc (use release). Elsewhere in code, it's a defensive coding measure. No, they are not the same thing.