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POHow can this Xcode Clang static analyzer warning be suppressed?
 

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  1. POHow can this Xcode Clang static analyzer warning be suppressed?
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    <blockquote> <p>"Potential leak of an object allocated on line <em>n</em> and stored into '<em>variable</em>'."</p> </blockquote> <p>Normally this is a very helpful analyzer warning, but there are a few situations where I get annoying false positives that I would like to suppress to keep my analyzer results clean. In the analyzer's defense, what it's noticing would definitely be a memory leak were it not for a release in another path of execution (to which it is blind).</p> <p>I'll elaborate on my situation. It happens in various flavors, but the general pattern is as follows:</p> <ol> <li>An object is allocated and its delegate is set.</li> <li>Something is done with the object. (A task started, a view displayed, etc).</li> <li>Execution of current method ends. (Enter Clang warning).</li> <li>Object decides its task is complete, sends delegate a message.</li> <li>Delegate releases object.</li> </ol> <p>This is not at all an esoteric design pattern, so I'm hoping suppression is possible. I know it can be avoided by storing the offending object in an ivar that is later released, but I greatly prefer to not add ivar pollution.</p>
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    1. USMatt Wilding
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      1. POHow can this Xcode Clang static analyzer warning be suppressed?
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    1. COIt strikes me as odd that an object's delegate retains it. Typically, an object retains it's delegate, and to have the delegate retain the object would make a retain cycle. I'm not saying there are ZERO cases where a delegate might want to retain (perhaps short-lived) the object, but it would seem relevant to know why that's the case here. From what's been said here, I'd say it's more kosher for the object to retain itself for the duration of the operation and subsequent delegate message than for the delegate to "take ownership of" the alloc/init implied retain.
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      1. USipmcc
    2. CO@ipmcc: While it is possible for an object to retain its delegate, and there are a few places in SDK where a class does just that, I would say it is more common to store a delegate as a weak reference, to avoid the retain cycle you mention. Either way, it is definitely not "typical" for an object to retain its delegate. In my case, some class created an object with alloc/init and and set itself as the delegate. As the owner of the class, the delegate later releases the object when the it is done. There is no contrived ownership happening here.
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      1. POHow can this Xcode Clang static analyzer warning be suppressed?
      1. USMatt Wilding
    3. CO@ipmcc - Matt is correct, the normal pattern is: Object A creates Object B and sets itself as Object B's delegate. Object A retains Object B. When Object A gets dealloced, it makes sure to unset itself as Object B's delegate, otherwise you may crash.
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