JsonDic parsing helper

JsonDic

struct JsonDic {
    let dic     : [String:AnyObject]
    
    func integer(key: String) throws -> Int {
        guard let s = dic[key] as? Int else { throw ResourceError.parseWrongType(key) }
        return s
    }
    
    func string(key: String) throws -> String {
        guard let s = dic[key] as? String else { throw ResourceError.parseWrongType(key) }
        return s
    }
    
    func dictionary(key: String) throws -> JsonDic {
        guard let d = dic[key] as? JsonDic else { throw ResourceError.parseWrongType(key) }
        return d
    }
}

enum ResourceError : Swift.Error {
    case parseType(String)
    case parseWrongType(String)
    case parseClosure
    case jsonParsing
    case serverErrorCode(Int)
}