'advancedBy' in Swift is unavailable

Question

I\'m not sure how to resolve the above error messages, I have tried to convert it to index b

Answer 1

In Swift 3, advancedBy() has been renamed to advanced(by: Int).

Additionally, substringWithRange has been renamed to substring(with: Range).

Answer 2

The error (sometimes more easily seen in the "Issues Navigator", by pressing option+4) says:

error: 'advancedBy' is unavailable: To advance an index by n steps call 'index(_:offsetBy:)' on the CharacterView instance that produced the index.

Thus you could do:

let r = testStr.index(testStr.startIndex, offsetBy: range.location) ..< testStr.index(testStr.startIndex, offsetBy: range.location + range.length)
let result = testStr[r]

Or

let start = testStr.index(testStr.startIndex, offsetBy: range.location)
let end = testStr.index(start, offsetBy: range.length)
let result = testStr[start ..< end]