'subscript' is unavailable: cannot subscript String with a CountableClosedRange, see the documentation comment for discussion

Question

In Swift 4, I\'m getting this error when I try to take a Substring of a String using subscript syntax.

\'subscript\' is unavaila

Answer 1

Your question (and self-answer) has 2 problems:

Subscripting a string with Int has never been available in Swift's Standard Library. This code has been invalid for as long as Swift exists:

let mySubstring: Substring = myString[1..<3]

The new String.Index(encodedOffset: ) returns an index in UTF-16 (16-bit) encoding. Swift's string uses Extended Grapheme Cluster, which can take between 8 and 64 bits to store a character. Emojis make for very good demonstration:

let myString = "