仅获取数字：

NSMutableString *result = [NSMutableString stringWithCapacity:phoneNumber.length];

NSScanner *scanner = [NSScanner scannerWithString:phoneNumber];
NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];

while ([scanner isAtEnd] == NO) 
{
  NSString *buffer;
  if ([scanner scanCharactersFromSet:numbers intoString:&buffer]) 
   {
      [result appendString:buffer];
   } 
   else 
   {
      [scanner setScanLocation:([scanner scanLocation] + 1)];
   }
}

NSLog(@"%@", result);