How can I use String substring in Swift 4? ‘substring(to:)’ is deprecated: Please use String slicing subscript with a ‘partial range from’ operator

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.

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