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    <p>First, you don't have constructors, you have two initializers:</p> <pre><code>- (id)initWithTitle:(NSString *)title; - (id)initWithTitle:(NSString *)title page:(NSString *)page; </code></pre> <p>As with most initializers, the goal is to setup some instance variables (not member variables).</p> <p>The first step is to identify your designated initializer. In your case, it could be:</p> <pre><code>- (id)initWithTitle:(NSString *)title page:(NSString *)page; </code></pre> <p>Which means that <code>- (id)initWithTitle:(NSString *)title;</code> would be implemented as others have described:</p> <pre><code>- (id)initWithTitle:(NSString *)_title { return [self initWithTitle:_title page:nil]; } </code></pre> <p>However, I would recommend against this pattern as it makes subclassing more error prone than it should be. In subclassing, you must always override the designated initializer <em>or</em> you must implement a new initializer that calls the designated initializer. Obviously, the more initializers you have, the more potential for bugs in subclassing you might introduce.</p> <p>Furthermore, this:</p> <pre><code>Foo *f = [[Foo alloc] initWithTitle: @"Foo!" page: nil]; </code></pre> <p>Is far more clear than this:</p> <pre><code>Foo *f = [[Foo alloc] initWithTitle: @"Foo!"]; </code></pre> <p>The first indicates quite specifically that you have thought about <code>page</code> and decided to explicitly set it to <code>nil</code> or otherwise rely on the class <code>Foo</code> to set the page reasonably. The second gives no such indication.</p> <p>Both subclassing and explicit indication of intention are the primary reasons why you will find a lack of such convenience methods across Cocoa (there are some, but most are quite old -- older than when the policy really became rule).</p>
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    1. COYou can't avoid the pattern when you are creating a category that introduces a new initializer and you simply want to call an existing initializer.
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