Then We test the character values with if and else. We use UnicodeScalar and shift letters 13 places depending on their values.
Return We return a string based on the values appended to our Character array. We test rot13 in the rest of the program.
func rot13(value: String) -> String {
// Empty character array.
var result = [Character]()
// Some ASCII constants.// A = 65// M = 77// Z = 90// a = 97// m = 109// z = 122
let upperA = 65
let upperM = 77
let upperZ = 90
let lowerA = 97
let lowerM = 109
let lowerZ = 122// Loop over utf8 values in string.for u in value.utf8 {
let s = Int(u)
var resultCharacter = Character(UnicodeScalar(s)!)
if s >= lowerA && s <= lowerZ {
if s >= lowerM {
resultCharacter = Character(UnicodeScalar(s - 13)!)
} else {
resultCharacter = Character(UnicodeScalar(s + 13)!)
}
} else if s >= upperA && s <= upperZ {
if s >= upperM {
resultCharacter = Character(UnicodeScalar(s - 13)!)
} else {
resultCharacter = Character(UnicodeScalar(s + 13)!)
}
}
// Append to Character array.
result.append(resultCharacter)
}
// Return String.
return String(result)
}
// Test the method.
let input = "Do you have any cat pictures?"
let result = rot13(value: input)
let roundTrip = rot13(value: result)
print(input)
print(result)
print(roundTrip)Do you have any cat pictures?
Qb lbh unir nal png cvpgherf?
Do you have any cat pictures?
Some notes. ROT13 is a terrible way to encrypt text. But this example helps us learn a programming language. We must access UnicodeScalars and manipulate character values in Swift.
A short review. A trick to manipulating strings in Swift is the use of UnicodeScalar. With this type we can shift characters based on their numeric values. The utf8 property also helps.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Aug 23, 2023 (edit).