The other major framework we import by default in iOS projects is Foundation, which provides fundamental data types for common concerns like dates and times, regular expressions, file I/O, and so on. We’ve already used two classes from Foundation: the NSURL and NSURLRequest that we used to populate the UIWebView.
Foundation also provides strings (as the NSString class) and collections (NSArray and NSDictionary), and in Objective-C, we would work with these as we would with any other class. However, in Swift, the language has taken more responsibility for strings and collections, and we can do a lot of common tasks without having to explicitly call methods on object instances. This makes Swift a lot easier to just get in and use.