var persons = [String](count:100, repeatedValue: "")

["Bert", "Daniel", "Claire", "Aaron", "", "", ... ""]

persons = persons.sorted {$0.localizedCaseInsensitiveCompare($1) == NSComparisonResult.OrderedAscending }

["", "", ... , "Aaron", "Bert", "Claire", "Daniel"]

["Aaron", "Bert", "Claire", "Daniel", "", "", ... , ""]

var persons = [String : Bool]()

persons["Bert"] = true
persons["Daniel"] = true
persons["Clair"] = true
persons["Clair"] = true
persons["Aaron"] = true
persons["Daniel"] = true
persons["Clair"] = true

var values = persons.keys.array

values.sort { $0.localizedCaseInsensitiveCompare($1) == NSComparisonResult.OrderedAscending }

persons = persons
            .filter( { $0.isEmpty == false } )
            .sorted {$0.localizedCaseInsensitiveCompare($1) == NSComparisonResult.OrderedAscending }