Thank you for the explanation. I only started learning Objective-C, Cocoa, iOS,
etc in August, so I'm still pretty much a newbie and appreciate learning
something new.
In this particular case, the selector that is the argument to the
performSelector: method is a callback selector for NSTimer and hence is known
to return void. Therefore, using the #pragma to turn off this message is safe.
Thanks for the insight.
Rick Aurbach
Aurbach & Associates, Inc.
On Jan 21, 2013, at 2:45 PM, Greg Parker <gpar...@apple.com> wrote:
> On Jan 21, 2013, at 12:20 PM, Rick Aurbach <r...@aurbach.com> wrote:
>> It appears to work great, but I find that the class's executeSelector:
>> method generates a warning message.
>>
>>> - (void) executeSelector:(NSTimer*)timer {
>>> if(self.target != nil) {
>>> if([self.target respondsToSelector:self.sel])
>>> [self.target performSelector:self.sel withObject:self];
>>> }
>>> else
>>> [self invalidate];
>>> }
>>
>> where sel is defined as @property(nonatomic) SEL sel;
>>
>> The line containing the performSelector:withObject: method generates
>> "PerformSelector may cause a leak because its selector is unknown".
>>
>> Ok, I agree that the selector is unknown, but we know from the previous line
>> that the target responds to it.
>
> That's not what it's complaining about. It's complaining because the ARC
> compiler cannot see the name of the method you are calling, so ARC doesn't
> know whether its return value needs to be released.
>
>
>> So I'd like to prevent this particular warning. I'm sure I ought to know how
>> do do this, but how do I go about removing this warning message? Ideally,
>> I'd like to do this on a file (or occurrence) basis, so that I can make sure
>> that other similar usages are similarly safe.
>
> If you know the selectors you are calling do not return a retained object,
> you can use #pragma clang diagnostic to disable warning
> -Warc-performSelector-leaks around that line.
>
>
> --
> Greg Parker gpar...@apple.com Runtime Wrangler
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