 Try using plain tuples
 */
 
-var letterLists = (
+var letterLists = [
     (loc: 0, alphabet: "ABCDEFGHIJKLMNOPQRSTUVWXYZ"),
     (loc: 1, alphabet: "BCDEFGHIJKLMNOPQRSTUVWXYZA"),
     (loc: 2, alphabet: "CDEFGHIJKLMNOPQRSTUVWXYZAB"),

    (loc: 23, alphabet: "XYZABCDEFGHIJKLMNOPQRSTUVW"),
    (loc: 24, alphabet: "YZABCDEFGHIJKLMNOPQRSTUVWX"),
    (loc: 25, alphabet: "ZABCDEFGHIJKLMNOPQRSTUVWXY")
)

var message = "abe lincoln"
var shift = 5

var newKey = (26+shift)%26
var newAlpha = letterLists.5.alphabet
//need to substitute 'newKey' in 'newAlpha' to find the 'newKey'th

var newMessage = ""

newKey = (26+shift)%26

var origmessage = ""
newAlpha = letterLists[newKey].alphabet

for i in newMessage.uppercaseString.characters {
    switch i {
