You should leave one side empty, hence the name “partial range”.
let newStr = str[..<index]
The same stands for partial range from operators, just leave the other side empty:
let newStr = str[index...]
Keep in mind that these range operators return a Substring
. If you want to convert it to a string, use String
‘s initialization function:
let newStr = String(str[..<index])
You can read more about the new substrings here.