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copied!<p>Here's a couple of observations which may or may not be relevant.</p> <ul> <li>The code you posted is absolutely OK from Obj-C's point of view.</li> <li>Instead of <code>[super init]</code> you should really call UIViewController's designated initializer, <code>initWithNibName:bundle:</code>.</li> <li>You named the method <code>initWithBaseURL:</code>, but it takes NSString as an argument. While that does match the declaration in @interface, make sure you don't expect baseURL to be an NSURL object somewhere else in your code.</li> <li>What happens when you remove <code>@private</code>? I suspect nothing changes with regard to the exception you see.</li> </ul> <p>Make sure you don't do this:</p> <pre><code>NSString *myURL = [NSString stringWithFormat:...]; // myURL is autoreleased SignInViewController *controller = [[SignInViewController alloc] initWithBaseURL: myURL]; // retains myURL because it's immutable [myURL release]; // does not crash because myURL has been *retained* // baseURL is left with 0 retain count </code></pre> <p>You can verify that sending <code>copy</code> to an NSMutableString does produce another object, while sending <code>copy</code> to an immutable NSString is equivalent to <code>retain</code>, just because wasting memory on exact copies of immutable objects is inefficient. If baseURL were indeed a <em>copy</em> of myURL, the crash would happen when the autorelease pool was drained.</p> <p>In other words, a mistake may be in one place, only to manifest itself in another. The above example is not too contrived.</p>

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