Cocoa Programming for OS X: The Big Nerd Ranch Guide

Working with Foundation Types

In Objective-C, a number of familiar types are implemented as classes as part of the Foundation framework: NSString, NSNumber, NSArray, NSDictionary, and NSSet. Because Cocoa was built for Objective-C, you will often run into these classes when working with the Cocoa APIs. The good news is that Apple has made transitioning between the Swift and Foundation (Objective-C) counterparts relatively painless. They are toll-free bridged, meaning that there is minimal computational cost in converting between the two.

Basic bridging

Swift types are automatically bridged to their Foundation counterparts:

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