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    <p>I found it! The answer was, of course, on NSHipster and relates to the <a href="http://nshipster.com/__attribute__/" rel="nofollow"><code>__attribute__</code> directive</a>.</p> <p>In my particular case, the <code>const</code> specifier seems to fit best: </p> <blockquote> <p>The const attribute specifies that a function does not examine any values except their arguments, and have no effects except the return value. Note that a function that has pointer arguments and examines the data pointed to must not be declared const. Likewise, a function that calls a non-const function usually must not be const.</p> </blockquote> <p>So I was going to declare my class method as:</p> <p><code> + (UIColor *)primaryTintColor __attribute__((const)); </code></p> <p>After adding the <code>__attribute__</code> directive as above, the code compiled without error and behaves as expected under Xcode 5.0.2 and the iOS SDK 7.0.</p> <p>But as others have pointed out in the comments below, methods resolve internally to a function that includes a pointer argument to resolve <code>self</code>, so <code>__attribute__((const))</code> is <em>never</em> appropriate for methods. In this case, while it's a simple call to <code>+[UIColor colorWithRed:green:blue:alpha:]</code> I'll leave it as it is, but when it gets more complex—say, to slightly customise the values for different devices—I may well use a static variable to cache the value and use performance profiling to quantify any improvement.</p>
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    1. POHow can I optimise the declaration of a function that always returns the same value for a given run?
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    1. POHow can I optimise the declaration of a function that always returns the same value for a given run?
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    1. COI'm glad you figured it out, but this doesn't affect **methods**, for the reasons given in my answer.
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      1. USJosh Caswell
    2. COThanks; I don't know much about compiler internals—is inclining the only possible optimisation here, or are there others that may apply?
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    3. COThere's not much the compiler can do to optimize message sends in ObjC in the way you're thinking about, because, as I said, objects can make decisions at runtime about which method to run in response to a message.
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