Swift - Get letters only from String

Question

I'm trying to get letters only from String in Swift.

For example:

let str = "he4ll5663#$#0o"
print(str.letters) // prints hello

Answer 1

Here is a way to do it using filter on the unicodeScalars of the String:

extension String {
    var letters: String {
        return String(unicodeScalars.filter(CharacterSet.letters.contains))
    }
}

let str = "he4ll5663#$#0o"
print(str.letters)  // hello

Thanks @MartinR for the suggestion to avoid using first! (in my original answer) by changing the filter to the unicodeScalars of the String.