How to create a color with an alpha value using SwiftUI? : <p>In <code>UIKit</code> to create a color with an alpha value there are different ways, for example:</p>

<pre><code>UIColor(red: 0, green: 0, blue: 0, alpha: 0.8)
</code></pre>

<p>but this method is not available on the corresponding class <code>Color</code> of <code>SwiftUI</code>.</p>

<p>What can I use?</p>
