How to bridge a long long C macro to Swift?
<p>In Foundation there is C macro <code>NSURLResponseUnknownLength</code> defined as a <code>long long</code>:</p>

<pre><code>#define NSURLResponseUnknownLength ((long long)-1)
</code></pre>

<p>Due to the way macros are bridged to Swift, this constant is accessible in an Objective-C application, but not in a Swift application.  How can I make macros like these visible to Swift?</p>

<p>I've tried wrapping the macro in a global C function in my bridging header:</p>

<pre><code>long long getNSURLResponseUnknownLength() {
    return NSURLResponseUnknownLength;
}
</code></pre>

<p>But accessing <code>getNSURLResponseUnknownLength()</code> causes the <code>Undefined symbols for architecture</code> build error.</p>