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    <p>Edit: this isn't working. I thought it was, but now I'm getting crashes I don't understand. If I figure it out, I'll come edit this more. Here's what I wrote before, which is wrong. Again, this is not working:</p> <blockquote> <p>I think I found the answer to this: Key-Value Coding.</p> <p>With Key-Value Coding, I can set up an instance variable of type id, and then dynamically identify the actual contents of the variable. I can put anything in it, even an int, and Key-Value methods will identify it for me. But what's even more awesome is that if I retreive the contents of a variable using Key-Value Coding, and the variable turns out to be an int, Key-Value Coding automatically turns it into an NSNumber for me.</p> <p>I will attempt to demonstrate.</p> <p>The main thing is to set up accessor statements for the variable I want to access. So, for this example, let's say the variable is called "identifyMe."</p> <pre><code>//in the interface: @property (copy) id accessIdentifyMe; //in the implementation: @synthesize accessIdentifyMe = identifyMe; </code></pre> <p>Now "identifyMe" is Key-Value Compliant. We're good to go.</p> <p>All I have to do is take the items in the variadic list, pass them into identifyMe one by one, and use Key-Value methods to identify the contents. Like so:</p> <pre><code>/*...assume all the following is happening inside a loop that </code></pre> <p>counts through the variadic list. I'll call the variadic list "variadicList." First, I take the current variadic item and put it into identifyMe, declaring it as type "id"*/ identifyMe = va_arg(variadicList, id);</p> <pre><code>/*Now I use a Key-Value method to check if identifyMe holds an </code></pre> <p>NSNumber. If it holds an int, it will automatically be returned as an NSNumber, you'll recall, so querying for an NSNumber is functionally the same as querying for an int.<br> Outside the loop I've set up a handy boolean called foundANumber in which to store the results of the query:*/ foundANumber = [[self valueForKey:@"identifyMe"] isKindOfClass:[NSNumber class]];</p> <p>That's given me the ability to separate the numbers from the objects. With that done, I can put the objects directly into my dictionary, and put the numbers into an NSNumber before I put them in the dictionary.</p> <p>And what this means at the other end, when calling this method from another object, is that I can call this method and put an int in the parameter list and not worry about causing a crash. Yay.</p> </blockquote> <p>Here's the reason this isn't working: KVC isn't magic. I thought it had some super special way of determining the type of a variable, but it doesn't. It just looks at the type declared in the accessor methods, and it can't independently verify any more than that. Darn. </p>
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