By referencing instance variables within the block, you're causing the block to retain self, and since self retains (copy'd) the block, you've got a retain cycle.
The easiest way to fix this is to break the retain cycle yourself. Doing
"[self setCompletionBlock:nil];" at the end of the block should be adequate.
Dave
On Sep 30, 2010, at 9:17 AM, Andreas Grosam wrote:
> I've subclassed a NSOperation and declared a completion block in the
> initializer as follows:
>
> - (id) initWithParameter:(id)parameter
> {
> self = [super init];
> if (self != nil) {
> [self setCompletionBlock:^{
> NSLog(@"operation completed");
> [someIvar release], someIvar = nil;
> }];
>
> // ... initialize ivars
> }
> return self;
> }
>
>
> The problem is now, once a completion block has been defined and set as shown
> above, the NSOperation instance will never be dealloced. I noticed, when
> -setCompletionBlock: returns, the retain count of the NSOperation instance
> has been incremented by one.
>
> When there is no completion block set, the NSOperation object will be
> deallocated as expected some time later when the operation finished.
>
> The -initWithParameter: method is invoked on the main thread.
>
> The code of the completion block is trivial: It logs to the console and
> simply releases certain ivars. So, there should no autoreleased object
> (namely the operation object itself) left in some unknown execution context
> possibly without a pool and hence leaking.
>
>
> As a side note: according the docs, the exact execution context for the
> completion block is undefined. So, I think this means, we should better use
> synchronization primitives when accessing ivars since the dealloc method
> might still executing, right?
>
>
> This is running on iOS.
>
>
> Any hints?
>
>
>
> Thanks in advance
> Andreas
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