Invalid escape sequence in literal with regex [duplicate]

Answer 1

I'm guessing that your intent was to escape the - characters. But that's not necessary (and is incorrect). If your intent was to match just dashes, you should remove those backslashes entirely:

let pattern = "^(0[0-9]{2,3}-)?([2-9][0-9]{6,7})+(-[0-9]{1,4})?$"

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Unrelated, but I'm suspicious of that + character. Did you really mean that you wanted to match one or more occurrences of [2-9][0-9]{6,7}? Or did you want to match exactly one occurrence?

Answer 2

Two character sequence \ - is not a valid escape sequence in Swift String. When you need to pass \ - to NSRegularExpression as pattern, you need to write \\- in Swift String literal.

So, your line should be something like this:

static let Regex_studio_tel = "^(0[0-9]{2,3}\\-)?([2-9][0-9]{6,7})+(\\-[0-9]{1,4})?$"

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ADDITION

As Rob commented, minus sign is not a special character in regex when appearing outside of [ ], so you can write it as:

static let Regex_studio_tel = "^(0[0-9]{2,3}-)?([2-9][0-9]{6,7})+(-[0-9]{1,4})?$"