How to find out if letter is Alphanumeric or Digit in Swift

Question

I want to count the number of letters, digits and special characters in the following string:

let phrase = "The final score was 32-31!"

I tried:

for tempChar in phrase {
    if (tempChar >= "a" && tempChar <= "z") {
       letterCounter++
    }
// etc.

but I'm getting errors. I tried all sorts of other variations on this - still getting error - such as:

could not find an overload for '<=' that accepts the supplied arguments

Answer 1

For Swift 5 see rustylepord's answer.

Update for Swift 3:

let letters = CharacterSet.letters let digits = CharacterSet.decimalDigits  var letterCount = 0 var digitCount = 0  for uni in phrase.unicodeScalars {     if letters.contains(uni) {         letterCount += 1     } else if digits.contains(uni) {         digitCount += 1     } } 

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(Previous answer for older Swift versions)

A possible Swift solution:

var letterCounter = 0 var digitCount = 0 let phrase = "The final score was 32-31!" for tempChar in phrase.unicodeScalars {     if tempChar.isAlpha() {         letterCounter++     } else if tempChar.isDigit() {         digitCount++     } } 

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Update: The above solution works only with characters in the ASCII character set, i.e. it does not recognize Ä, é or ø as letters. The following alternative solution uses NSCharacterSet from the Foundation framework, which can test characters based on their Unicode character classes:

let letters = NSCharacterSet.letterCharacterSet() let digits = NSCharacterSet.decimalDigitCharacterSet()  var letterCount = 0 var digitCount = 0  for uni in phrase.unicodeScalars {     if letters.longCharacterIsMember(uni.value) {         letterCount++     } else if digits.longCharacterIsMember(uni.value) {         digitCount++     } } 

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Update 2: As of Xcode 6 beta 4, the first solution does not work anymore, because the isAlpha() and related (ASCII-only) methods have been removed from Swift. The second solution still works.

Answer 2

Use the values of unicodeScalars

let phrase = "The final score was 32-31!"
var letterCounter = 0, digitCounter = 0
for scalar in phrase.unicodeScalars {
    let value = scalar.value
    if (value >= 65 && value <= 90) || (value >= 97 && value <= 122) {++letterCounter}
    if (value >= 48 && value <= 57) {++digitCounter}
}
println(letterCounter)
println(digitCounter)