What is the best way to determine if a string contains a character from a set in Swift

Question

I need to determine if a string contains any of the characters from a custom set that I have defined.

I see from this post that you can use rangeOfString to determine

Answer 1

You can create a CharacterSet containing the set of your custom characters and then test the membership against this character set:

Swift 3:

let charset = CharacterSet(charactersIn: "aw")
if str.rangeOfCharacter(from: charset) != nil {
    print("yes")
}

For case-insensitive comparison, use

if str.lowercased().rangeOfCharacter(from: charset) != nil {
    print("yes")
}

(assuming that the character set contains only lowercase letters).

Swift 2:

let charset = NSCharacterSet(charactersInString: "aw")
if str.rangeOfCharacterFromSet(charset) != nil {
    print("yes")
}

Swift 1.2

let charset = NSCharacterSet(charactersInString: "aw")
if str.rangeOfCharacterFromSet(charset, options: nil, range: nil) != nil {
    println("yes")
}

Answer 2

func isAnyCharacter( from charSetString: String, containedIn string: String ) -> Bool
{
    return Set( charSetString.characters ).isDisjointWith( Set( string.characters) ) == false
}

Answer 3

Swift 3 example:

extension String{
    var isContainsLetters : Bool{
        let letters = CharacterSet.letters
        return self.rangeOfCharacter(from: letters) != nil
    }
}

Usage :

"123".isContainsLetters // false

Answer 4

From Swift 1.2 you can do that using Set

var str = "Hello, World!"
let charset: Set<Character> = ["e", "n"]

charset.isSubsetOf(str)     // `true` if `str` contains all characters in `charset`
charset.isDisjointWith(str) // `true` if `str` does not contains any characters in `charset`
charset.intersect(str)      // set of characters both `str` and `charset` contains.

Swift 3 or later

let isSubset = charset.isSubset(of: str)        // `true` if `str` contains all characters in `charset`
let isDisjoint = charset.isDisjoint(with: str)  // `true` if `str` does not contains any characters in `charset`
let intersection = charset.intersection(str)    // set of characters both `str` and `charset` contains.
print(intersection.count)   // 1

Answer 5

Use like this in swift 4.2

    var string = "Hello, World!"
    let charSet = NSCharacterSet.letters
    if string.rangeOfCharacter(from:charSet)?.isEmpty == false{  
      print ("String contain letters");
    }

Answer 6

swift3

var str = "Hello, playground"
let res = str.characters.contains { ["x", "z"].contains( $0 ) }