title: What makes Swift's "Optional" safer than Objective-C's "nil"?
body: <p><a href="https://developer.apple.com/documentation/swift/optional" rel="noreferrer">Apple seems to claim</a> that the <code>Optional</code> type in Swift is safer than <code>nil</code> in Objective-C, but I don't understand why this is so.</p>
  
  <p>What are the salient differences in implementation that make <code>Optional</code>s safer than <code>nil</code>, and how will this affect my code?</p>