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    <p>This line:</p> <pre><code>self = [unarchiver decodeObjectForKey:kDateDataKey]; </code></pre> <p>is going to give you problems.</p> <p>What you're doing is to allocate a DateTracker object (<code>[DateTracker alloc]</code>), then create a new DateTracker object (by <code>-decodeObjectForKey:</code>) and make the "self" pointer refer to the new object. There are two problems with that:</p> <ul> <li>you no longer have a reference to the old object, so it's leaked</li> <li>the new object is not retained, so it goes away (or causes a crash if you try to release it)</li> </ul> <p>I would say the approach of having an object replace itself is a bit suspect. Perhaps you would do better to move the <code>filePath</code> variable outside of the <code>DateTracker</code> object, and unarchive it by something like:</p> <pre><code>DateTracker *currentTracker = [[DateTracker unarchiveFromFile:filePath] retain]; </code></pre> <p>where <code>unarchiveFromFile:</code> is a class method that does essentially what <code>initFromFile</code> did, without messing with <code>self</code>:</p> <pre><code>+ (DateTracker*)unarchiveFromFile:(NSString *)filePath { DateTracker *result = nil; if ([[NSFileManager defaultManager] attributesOfFileSystemForPath:filePath error:NULL]) { NSData *data = [[NSMutableData alloc] initWithContentsOfFile:filePath]; NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; result = [unarchiver decodeObjectForKey:kDateDataKey]; [unarchiver finishDecoding]; [unarchiver release]; [data release]; } return result; } </code></pre>
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    1. USDavid Gelhar
    1. USDavid Gelhar
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    1. COAaaaah I see. Would it still work if I kept the file path initialiser inside the DateTracker class though? So the first line of the unarchiveFromFile method would get the filePath string.
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    2. COAlso, what would happen if I just changed my initFromFile method into a class method and called it like so: DateTracker *currentTracker = [DateTracker initFromFile]. Would it autorelease when it wasn't being used? Or should I explicitly retain and release it? Or would that just be a bad idea anyway...
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    3. COSure, `filePath` could be a static member of the DateTracker class. The point about autorelease is that `decodeObjectForKey:` is going to return an autoreleased object (according to the normal Cocoa memory management conventions, since it doesn't have "Alloc" or "Copy" in its name, you know that it returns an autoreleased object). So, you need to retain/release it if you want to hang on to it.
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