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

var myString = "hell"
let index = 4
let character = "o" as Character

myString.insert(
    character, at:
    myString.index(myString.startIndex, offsetBy: index)
)

print(myString) // "hello"

Careful: make sure that index is bigger than or equal to the size of the string, otherwise you'll get a crash.