Quickest way to concatenate strings in Swift 2
<p>Which is the quickest, and most efficient way to concatenate multiple strings in Swift 2?</p>

<pre><code>// Solution 1...
let newString:String = string1 + " " + string2
// ... Or Solution 2?
let newString:String = "\(string1) \(string2)"
</code></pre>

<p>Or is the only differentiation the way it looks to the programmer?</p>