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POCocoa: Why set 'nil' prior to the method call?
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2011-04-26T01:47:25.930
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2011-04-27T12:37:25.187
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2011-04-26T01:54:55.620
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I have been working though the examples in <a href="http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/LowLevelFileMgmt/Articles/EnumADir.html#//apple_ref/doc/uid/20000783-BAJFBAAH" rel="nofollow">Using a Directory Enumerator</a> in the Apple Low-Level File sections. Here is a code snippet: <pre><code>for (NSURL *url in enumerator) { // Error-checking is omitted for clarity. NSNumber *isDirectory = nil; [url getResourceValue:&isDirectory forKey:NSURLIsDirectoryKey error:NULL]; if ([isDirectory boolValue]) { NSString *localizedName = nil; [url getResourceValue:&localizedName forKey:NSURLLocalizedNameKey error:NULL]; NSNumber *isPackage = nil; [url getResourceValue:&isPackage forKey:NSURLIsPackageKey error:NULL]; if ([isPackage boolValue]) { NSLog(@"Package at %@", localizedName); } else { NSLog(@"Directory at %@", localizedName); } } </code></pre> } Why are <code>localizedName</code>, <code>isPackage</code>, and <code>isDirectory</code> being set to <code>nil</code> prior to the relevant calls to the <code>getResourceValue</code> method? Is this just an over abundance of caution or is this required? As I read <a href="http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/Reference/Reference.html#//apple_ref/occ/instm/NSURL/fileReferenceURL" rel="nofollow">the docs</a> for <code>getResourceValue:forKey:error:</code> it seems redundant: <blockquote> Return Value YES if value is successfully populated; otherwise, NO. Discussion value is set to nil if the requested resource value is not defined for the URL. In this case, the method still returns YES. </blockquote> Am I missing something?
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Cocoa: Why set 'nil' prior to the method call?
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