The most popular mechanism to send structured data over a network is to encode it in JSON, which stands for JavaScript Object Notation. This provides a hierarchical tree data structure that can store simple numeric, logical, and string-based types along with the array and dictionary representations.

Both Mac OS X and iOS come with a built-in parser for JSON documents, in the NSJSONSerialization class. This provides a means to parse a data object and return an NSDictionary that contains the key/value pairs of a JSON object or an NSArray to represent JSON arrays. Other literals are parsed and represented as the NSNumber or NSString values.

The JSON parser uses JSONObjectWithData to create an object from an NSData object containing a string. This is typically the format returned by network APIs and can be created from an existing string using dataUsingEncoding with one of the built-in encoding types, such as NSUTF8StringEncoding.

A simple JSON array of numbers can be parsed as follows...