Check OS version using Swift on Mac OS X
<p>I'm building an application that needs to check what version of OS X is installed on a Mac. It is built against 10.9 Mavericks, but all of the Swift APIs are pretty much 10.10 only.</p>

<p>I'm trying to use the following, however it does not compile against the 10.9 SDK since it does not have these APIs, I know how to use <code>if #available(OSX 10.10, *)</code> to conditionally compile as per the different versions, however because <code>NSProcessInfo</code> is a 10.10+ API I can't use it to check to see if the Mac is running 10.9. This is the code I have so far (however it does not compile against the 10.9 SDK):</p>

<pre><code>let osVersion = NSProcessInfo.processInfo().operatingSystemVersion
if osVersion.minorVersion == 9 {
    //  Do something for OS X 10.9 Mavericks
} else {
    // Do something for anything not Mavericks (10.10+)
}
</code></pre>

<p>Is there another way to check what OS the Mac is running in 10.9? Essentially I could wrap the above code with:</p>

<pre><code>if #available(OSX 10.10, *) {
    let osVersion = NSProcessInfo.processInfo().operatingSystemVersion
    // Check OS version
} else {
    // Check OS version using a 10.9 API
}
</code></pre>

<p>I just don't know what to fill in for the <code>// Check OS version using a 10.9 API</code> section of that code block.</p>