Re: There's obviously something I don't understand about NSDate.
Re: There's obviously something I don't understand about NSDate.
- Subject: Re: There's obviously something I don't understand about NSDate.
- From: Dave Fernandes <email@hidden>
- Date: Sat, 17 Mar 2012 18:57:29 -0400
Yes, [NSDate date] returns an autoreleased object. So you need to retain it if you want to use it later. Once you are done with it, you should release it. See:
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmRules.html#//apple_ref/doc/uid/20000994-SW6
If a Cocoa method name doesn't begin with “alloc”, “new”, “copy”, or “mutableCopy”, then the returned object is autoreleased.
Dave
On 2012-03-17, at 6:38 PM, G S wrote:
> I have a member variable to hold an NSDate:
>
> NSDate* _firstBadAccuracyTime;
>
> At some point, something happens and I set this value to "now":
>
> _firstBadAccuracyTime = [NSDate date];
>
> On my next trip through this function, I calculate how long it has been
> since I set this date:
>
> NSDate* now = [NSDate date];
> if([now timeIntervalSinceDate:_firstBadAccuracyTime] >
> BAD_ACCURACY_TIME)
>
> then CRASH: BAD ACCESS
>
> _firstBadAccuracyTime still contains a valid address, but the object
> must've been released. Why? If I add a retain where I assign it, the
> crash doesn't happen. I added autorelease, but then got a crash on
> releasing an object I hadn't allocated (which makes me think it's already
> autoreleased).
>
> Thanks for any insight!
>
> Gavin
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