code>NSArray</code> is has unusual performance characteristics).</p>

<h2>Bridging to Objective-C</h2>

<p>Any bridged <code>Array</code> can be implicitly converted to an <code>NSArray</code>.
When <code>Element</code> is a <code>class</code> or <code>@objc</code> protocol, bridging takes O(1)
time and O(1) space.  Other <code>Array</code>s must be bridged
element-by-element, allocating a new object for each element, at a
cost of at least O(<code>count</code>) time and space.</p>

<h2>Bridging from Objecti