insert a string into another string at a specific index in swift

In Swift, you can use the insert(_:at:) method to insert a character or substring at a specific index of a string. Here's an example:

main.swift
var myString = "Hello World"
let index = myString.index(myString.startIndex, offsetBy: 6)
myString.insert(contentsOf: "Awesome ", at: index)
print(myString) // Output: "Hello Awesome World"
190 chars
5 lines

In the above example, we first define a string myString, and then create an index that points to the 7th character in the string ("W"). We then use the insert(contentsOf:at:) method to insert the substring "Awesome " at the specified index.

Note that the insert(contentsOf:at:) method can also be used to insert individual characters, or even other collections of characters, such as arrays or other strings.