Objective-c regex to check phone number

How
to validate a phone number (NSString *) in objective-c?
Rules:

• minimum 7
  digits


• maximum 10
  digits


• the first digit must be 2, 3, 5, 6, 8 or
  9

Thanks

Answer

You can use a regular expressions library
(like RegexKit, etc), or you could use regular expressions through
NSPredicate (a bit more obscure, but doesn't require
third-party libraries). That would look something like
this:

NSString *phoneNumber =
            ...;
NSString *phoneRegex = @"[235689][0-9]{6}([0-9]{3})?";
            
NSPredicate *test = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",
            phoneRegex]; 
BOOL matches = [test
            evaluateWithObject:phoneNumber];

If
you're on iPhone, then iOS 4 introduced NSRegularExpression,
which would also work. The NSPredicate approach works on both
Mac and iPhone (any version).