Objective-c regex to check phone number

Question

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 1

In iOS 4.0+ there are built in classes to do this, NSRegularExpression

In everything else you can either use a 3rd party RegEx library, or use an NSPredicate if your needs are narrow enough

Answer 2

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).

Answer 3

Please don't use your own regex for the phone-number. Don't.

The format of phone numbers changes across the country, and your app might be used outside of your own country.

Instead, use what Apple provides, as Josh says. See here.

Answer 4

The NSDataDetector class, available in iOS 4.0 and later, is a specialized subclass of NSRegularExpression that has explicit support for detecting phone numbers.