this code works for your json string
var obj = JsonConvert.DeserializeObject<RootObject>(appJsonData);
public class Result
{
public string kind { get; set; }
public List<object> features { get; set; }
public List<string> supportedDevices { get; set; }
public bool isGameCenterEnabled { get; set; }
public List<string> screenshotUrls { get; set; }
public List<object> ipadScreenshotUrls { get; set; }
public string artworkUrl60 { get; set; }
public string artworkUrl512 { get; set; }
public string artistViewUrl { get; set; }
public int artistId { get; set; }
public string artistName { get; set; }
public double price { get; set; }
public string version { get; set; }
public string description { get; set; }
public string currency { get; set; }
public List<string> genres { get; set; }
public List<string> genreIds { get; set; }
public string releaseDate { get; set; }
public string sellerName { get; set; }
public string bundleId { get; set; }
public int trackId { get; set; }
public string trackName { get; set; }
public string primaryGenreName { get; set; }
public int primaryGenreId { get; set; }
public string releaseNotes { get; set; }
public string formattedPrice { get; set; }
public string wrapperType { get; set; }
public string trackCensoredName { get; set; }
public List<string> languageCodesISO2A { get; set; }
public string fileSizeBytes { get; set; }
public string contentAdvisoryRating { get; set; }
public double averageUserRatingForCurrentVersion { get; set; }
public int userRatingCountForCurrentVersion { get; set; }
public string artworkUrl100 { get; set; }
public string trackViewUrl { get; set; }
public string trackContentRating { get; set; }
}
public class RootObject
{
public int resultCount { get; set; }
public List<Result> results { get; set; }
}
EDIT
var obj = JsonConvert.DeserializeObject<JObject>(appJsonData)["results"][0] as JObject;
var app = obj.ToObject <Result>();