Question

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A comprehensive regex for phone number validation

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

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).