How to apply regex and/or clean a telephone string?

I have a NSString that contains fax telephone numbers. Sometimes I get different 开发者_C百科formats entered for example: (877) xxx-xxxx or 877-xxx-xxxx.

How do I get about cleaning the NSSString so that all I get is XXXxxxxxx.

Thanks

Using NSCharacterSet and NSMutableCharacterSet you can solve this problem in two ways.

1. If you already know the characters that you want to remove.

   NSCharacterSet *charSet = [NSCharacterSet characterSetWithCharactersInString:@"+-(),. "];
   NSArray *arrayWithNumbers = [str componentsSeparatedByCharactersInSet:charSet];
   NSString *numberStr = [arrayWithNumbers componentsJoinedByString:@""];
   

2. If you don't know the characters, you can use the different character sets available already

   NSMutableCharacterSet *charSet = [NSMutableCharacterSet new];
   [charSet formUnionWithCharacterSet:[NSCharacterSet whitespaceCharacterSet]];
   [charSet formUnionWithCharacterSet:[NSCharacterSet punctuationCharacterSet]];
   [charSet formUnionWithCharacterSet:[NSCharacterSet symbolCharacterSet]];
   NSArray *arrayWithNumbers = [str componentsSeparatedByCharactersInSet:charSet];
   NSString *numberStr = [arrayWithNumbers componentsJoinedByString:@""];