Re: Questions regarding release
Re: Questions regarding release
- Subject: Re: Questions regarding release
- From: Rob Petrovec via Cocoa-dev <email@hidden>
- Date: Thu, 26 Sep 2019 18:02:54 -0600
> On Sep 26, 2019, at 5:43 PM, James Walker via Cocoa-dev
> <email@hidden> wrote:
>
> On 9/26/19 4:20 PM, Gabriel Zachmann via Cocoa-dev wrote:
>>> The issue in the below code to my eye is that you allocate a path with
>>> CGPathCreateWithRect (+1) but then don't release it.
>>>
>>> In that case, I am wondering:
>>> doesn't ownership pass to the textlayer ?
>>> If yes, shouldn't textlayer release the path when it gets destroyed by the
>>> ARC?
>>>
>>> CALayer will indeed release shadowPath when it’s deallocated. However,
>>> CALayer.setShadowPath doesn’t expect to be passed a +1 reference, so it
>>> will retain/copy its argument, and it’s that retain which will be balanced
>>> by the release during object destruction. Functions and methods generally
>>> do not expect to be passed +1 objects.
>> So, if I understand you correctly, I should do this:
>> textlayer.shadowPath = CGPathCreateWithRect( textlayer.bounds, NULL );
>> CFRelease( textlayer.shadowPath )
>> ?
>> Is that correct?
>
> That's not completely clear. The documentation on shadowPath says "The value
> of this property is retained using the Core Foundation retain/release
> semantics". However, a comment in CALayer.h says "Upon assignment the path
> is copied." If that's true, you'd be releasing the copy, not the original.
> It would be safer to say:
>
> CGPathRef thePath = CGPathCreateWithRect( textlayer.bounds, NULL );
> textlayer.shadowPath = thePath;
> CFRelease( thePath );
If the path returned by CGPathCreateWithRect is immutable, which I
think it is, then the copy made by shadowPath would likely be just a retain.
However, I agree that assigning it to a variable is the better, less fragile,
and more readable method.
—Rob
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