Custom font size for Text in SwiftUI : <p>I have a label in my view that I want to use the system font size in medium, with a size of 21 points.<br>
I created a custom extension to re-use the font created:</p>

<pre><code>extension Font {
    static var primaryButton: Font {
        return Font.custom("SFUIDisplay-Light", size: 21)
    }
}
</code></pre>

<p>However, this does not have any effect. I changed the string to <code>HelveticaNeue-UltraLight</code> and it did work, so I'm guessing that <code>SFUIDisplay-Light</code> is simply the incorrect font name.<br>
In font book, it says <code>SFProText-Light</code>, but that also did not work for me.</p>

<p>What is the correct font name of the San Francisco font in SwiftUI?<br>
Or: how can I set the font size using the system font?</p>
