var people = [[String : String]]()

class Database {
    class func addPerson(dict: [String : String]) -> Void {
        people.append(dict)
    }
    class func getPerson(name : String) -> [String : String]? {
        for person in people {
            if person["name"] == name {
                return person
            }
        }
        return nil
    }
}

Database.addPerson([
    "name" : "Fred",
    "age" : "19"
])

Database.addPerson([
    "name" : "Billy",
    "age" : "21"
])

Database.getPerson("Billy") // [name: Billy, age: 21]
Database.getPerson("David") // nil