More complete example

gistfile1.swift

var text: String!

override func viewDidLoad() {
    super.viewDidLoad()

    let url = NSBundle.mainBundle().URLForResource("test", withExtension: "json")!
    
    var files = [String : NSFileWrapper]()
    var error: NSError?
    files["file.json"] = NSFileWrapper(URL: url, options: nil, error: &error)

    if let file = files["file.json"],
        contents = file.regularFileContents,
        stringContents = NSString(data: contents, encoding: NSUTF8StringEncoding)  {
            text = stringContents
            print(text)
    }
}