StackOverflow2013

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POObjective-C: Get list of subclasses from superclass
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copied!<p>In Objective-C is there a way to ask a Class if there are any Subclass implementations.</p> <p>I have a Base class which has multiple subclasses. I would like to loop through all the subclasses and perform a class selector on each of them.</p> <p><strong>Edit</strong>:</p> <p>I have a set of classes that can process certain types of data. Each of the processors subclass a base class that provides methods that each processor needs.</p> <p>Each class knows what data it can process and some classes can process certain types of data better than others.</p> <p>I would like to have a class method on each class that would provide a response back to a factory class that says yes i can process that data, and give a indication of how well it can process it.</p> <p>The factory would then make the decision on which class to instantiate based on which class says it can process the data the best.</p> <p>I have also found this question from 2009 (I did search before I posted this but didn't find anything) <a href="https://stackoverflow.com/questions/1810628/discover-subclasses-of-a-given-class-in-obj-c">Discover subclasses of a given class in Obj-C</a>.</p> <p><strong>Edit 2</strong>:</p> <p>The <code>+ (void)load</code> method looks to be the perfect solution to what I am looking for. So I now have the following:</p> <pre><code>+ (void)registerSubclass:(Class)subclass { NSLog(@"Registered %@", subclass); } </code></pre> <p>In my base class the this is my subs.</p> <pre><code>+(void)load { [BaseSwitch registerSubclass:[self class]]; } </code></pre> <p>This now displays a debug message for each of the subclasses.</p> <p>My next question is (probably a stupid one), how do I store the classes that get registered in the registerSubclass method. Is there a way to have class variable that I can read later?</p> <p><strong>Edit 3</strong>:</p> <p>Found some example code here <a href="http://cocoawithlove.com/2009/07/simple-extensible-http-server-in-cocoa.html" rel="nofollow noreferrer">A simple, extensible HTTP server in Cocoa</a></p> <p>Which has left me with the following, seems pretty simple after all is said and done. But I thought I would put it here for future reference.</p> <pre><code>@implementation BaseSwitch static NSMutableArray *registeredSubclasses; + (void)registerSubclass:(Class)subclass { if (registeredSubclasses == nil) { registeredSubclasses = [[NSMutableArray alloc] init]; } [registeredSubclasses addObject:subclass]; NSLog(@"Registered %@", subclass); } + (void)logSubclasses { for (int i = 0; i < [registeredSubclasses count]; i++) { NSLog(@"%@", [registeredSubclasses objectAtIndex:i]); } } @end </code></pre> <p>Thanks for everyones suggestions, I will leave the question unanswered for a couple more days incase something else comes up.</p>

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