将字符串与 swift 中的正则表达式部分匹配

Question

I'm trying to create regexp with format "dd-dd-dd" in Swift

I came up with this :

(\d{1,2})(-)(\d{1,2})(-)(\d{1,2})

This pattern gives me correct result if the string is given as a whole. Example :

12-32-42 -> correct
2-32-1   -> correct
2--32-3  -> incorrect

I will be using this pattern in textfields. What I would like to know is if the typed string is heading towards positive regexp check. Example :

12     -> correct
-12-32 -> correct
12-    -> correct
-12--  -> incorrect

I will be grateful for any help you can provide.

Answer 1

One option could be to list to possible combinations in an alternation :

^(?:\d{1,2}-\d{1,2}-\d{1,2}|\d{1,2}-|-\d{1,2}-\d{1,2}|\d{1,2})$

Regex demo