title: Type Casting in swift
body: <p>I am bit confused with typecasting in Swift.</p>
  <p>Have a small doubt.
  What is the difference between <code>as?</code>,<code>as!</code> and only <code>as</code>.
  And can we say &quot;as&quot; is similar to <code>is</code>.</p>
  <p>Thanks in advance.</p>