On Apr 23, 2014, at 03:01 , Dave <[email protected]> wrote:
> If I changed the names of commandDownloadImageWithFileURLString to be
> newCommandDownloadImageWithFileURLString, this would cause it to release
> myImage on each iteration rather than using Autorelease?
It would remove one — and perhaps the only — reason for ARC to use autorelease,
but there’s no way of knowing whether there are others, hidden from you. For
example, even if you create a new image using some alloc/init that returns the
created object with +1 ownership, it may have already been autoreleased before
it gets back to you.
The outcome is also going to vary with the version of clang you compiled with,
and the OS version you’re running on. The current clang already uses
autorelease less often than the original implementation, and Cocoa classes may
get converted from MRR to ARC gradually over OS releases.
It seems to me that the best practice is:
— Return objects with +1 ownership when semantically appropriate (when the
caller gets an object that is conceptually new).
— Investigate memory usage with Instruments, preferably on supported older OS
versions too.
— Bracket problem areas with @autoreleasepool{} only you’ve identified a
problem area with Instruments.
— Don't gratuitously insert @autoreleasepool{} in loops “just for safety”.
> Is there anyway of telling if an Object is in “autorelease” state? I mean
> just for testing, I wouldn’t rely on this in shipping code.
I don’t think so.
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