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 if a string contains another string. This, of course, also works for characters if you test each character one at a time.

I'm wondering what the best way to do this is.

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

ONE LINE Swift4 solution to check if contains letters:

CharacterSet.letters.isSuperset(of: CharacterSet(charactersIn: myString) // returns BOOL 

Another case when you need to validate string for custom char sets. For example if string contains only letters and (for example) dashes and spaces:

let customSet: CharacterSet = [" ", "-"] let finalSet = CharacterSet.letters.union(customSet) finalSet.isSuperset(of: CharacterSet(charactersIn: myString)) // BOOL 

Hope it helps someone one day:)