title: What does array.map(CGFloat.init(_:)) do?
body: <p>I found this in some open source code.</p>
  <p>I am familiar with map(), but not the <code>CGFloat.init(_:))</code> part.</p>
  <p>The Swift code is as follows:</p>
  <pre><code>if let array = propertyListValue as? [Int], array.count == 3 || array.count == 4 {
          let floats = array.map(CGFloat.init(_:))
  }
  </code></pre>
  <p>Not sure what to look for in docs. I know what <code>_ name : Type</code> means in a function declaration... but just confused by this use case.</p>