Check if NSString contains alphanumeric + underscore characters only

Question

I\'ve got a string that needs to be only a-z, 0-9 and _

How do I check if the input is valid? I\'ve tried this but it accepts letter like å,ä,ö,ø etc.

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Answer 1

Create your own character set using [NSCharacterSet characterSetWithCharactersInString:], then trim as you were doing to see if the returned string has a length value.

Or you could use invertedSet to remove all non-set characters, if that would help to produce a cleaned string.