Is retainCount giving me the correct information for my NSDate?

Question

I have NSDate property

In .h

...
@interface MyAppDelegate : NSObject <UIApplicationDelegate> {
...
      NSDate *pageStartDate;
...
}
...
@property (nonatomic, retain) NSDate *pageStartDate;
...

In .m

...
-(void)myMethod
{
   ...
   // set date of start showing page
   NSDate *tempStartDate = [NSDate date];
   [tempStartDate retain];
   pageStartDate = tempStartDate;
   [tempStartDate release];
   ...
}
...

After running this code the [tempStartDate retainCount] = 1 - is it normal? If I write self.pageStartDate = tempStartDate than [pageStartDate retainCount] = 2.

Is there right use of NSDate, or not is?

If you write @syncronize pageStartDate; it mean that retain count 1 is normal — Viktor Apoyan, Jun 02 '11 at 12:04
I wrote @synchronize, of course. I'm needed in property 'pageStartDate', but when I use `self.pageStarDate` this retainCount increases to 2. — Sound Blaster, Jun 02 '11 at 12:45

score 1 · Answer 1 · answered Jun 02 '11 at 12:14

If you don't write self.pageStartDate it won't use the property, so yes, the retain count of 1 is expected. Also, note that this instance is autoreleased (because you created it with [NSDate date]), so it will be released later.

If you were using the property, you wouldn't need the retain and release statements.

score 0 · Accepted Answer · edited May 23 '17 at 10:00

0

The problem isn't just your NSDate its because you've used retainCount

Annotation:

NSDate *tempStartDate = [NSDate date]; // No alloc, retain, copy, or mutableCopy - so assume autoreleased instance
[tempStartDate retain]; // You call retain - you own this now
pageStartDate = tempStartDate; // Not going through the setter. :(
[tempStartDate release];  // You've released this correctly, except for the step above.
                          // pageStartDate is now pointing to a garbage pointer.

You've done the right thing by releasing what you've retained, but pageStartDate didn't hold on to the value.

Try this

self.pageStartDate = [NSDate date];

Since you are using retain for the pageStartDate property, this will retain the value for you.

But - trying to use retainCount to check your memory management is, basically, doing it wrong.

edited May 23 '17 at 10:00

Community

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answered Jun 02 '11 at 12:05

Abizern

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In which case accepting my answer and/or upvoting is the usual way of thanking someone on SO. – Abizern Jun 02 '11 at 12:39
But I think about this: `self.pageStartDate = [NSDate date]; NSLog(@"[pageStartDate retainCount] = %i", [pageStartDate retainCount]);` In Log I see `[pageStartDate retainCount] = 2` - is it normal? Because I have ONE `release` of `pageStarDate` in my code - in `-(void)dealloc` – Sound Blaster Jun 02 '11 at 12:39
1

DON'T USE `retainCount`. It tells you nothing about running code. See the link in my answer. Just worry about the memory management rules and don't look at what `retainCount` tells you. Remember - the date value is `autoreleased` - which means it will be released when the autorelease pool drains which may no be immediately. – Abizern Jun 02 '11 at 12:42
Oups, I didn't catch link in your answer. Thank again! – Sound Blaster Jun 02 '11 at 12:47

Is retainCount giving me the correct information for my NSDate?

2 Answers2