How to add a character at a particular index in string in Swift

Question

I have a string like this in Swift:

var stringts:String = \"3022513240\"

If I want to change it to string to something like this: \"(

Answer 1

Maybe this extension for Swift 4 will help:

extension String {
  mutating func insert(string:String,ind:Int) {
    self.insert(contentsOf: string, at:self.index(self.startIndex, offsetBy: ind) )
  }
}