StackOverflow2013

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POaddObserverForName and removing observer
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copied!<p>On Cocoa code with ARC enabled, I tried to observe Window closing events like below.</p> <pre><code>ScanWindowController * c = [[ScanWindowController alloc] initWithWindowNibName:@"ScanWindowController"]; [scanWindowControllers addObject:c]; [c showWindow:nil]; NSMutableArray *observer = [[NSMutableArray alloc] init]; observer[0] = [[NSNotificationCenter defaultCenter] addObserverForName:NSWindowWillCloseNotification object:nil queue:nil usingBlock:^(NSNotification *note) { [scanWindowControllers removeObject:c]; [[NSNotificationCenter defaultCenter] removeObserver:observer[0]]; }]; </code></pre> <p>I thought this will remove all the references to the controller (c) after closing Window. But actually, this code does not dealloc ScanWindowController after closing Window. If I wrote like below using weak reference to the controller, dealloc of ScanWindowController is called.</p> <pre><code>ScanWindowController * c = [[ScanWindowController alloc] initWithWindowNibName:@"ScanWindowController"]; [scanWindowControllers addObject:c]; [c showWindow:nil]; __weak ScanWindowController * weak_c = c; NSMutableArray *observer = [[NSMutableArray alloc] init]; observer[0] = [[NSNotificationCenter defaultCenter] addObserverForName:NSWindowWillCloseNotification object:nil queue:nil usingBlock:^(NSNotification *note) { [scanWindowControllers removeObject:weak_c]; [[NSNotificationCenter defaultCenter] removeObserver:observer[0]]; }]; </code></pre> <p>Why does the first code not work?</p>

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