NSCharacterSet *setToRemove =
[[ NSCharacterSet characterSetWithCharactersInString:@"0123456789"]
invertedSet ];
NSString *strPhone = @"";
strPhone? = [[@"qwe123" componentsSeparatedByCharactersInSet:setToRemove] componentsJoinedByString:@""];
////////////////////////////////////////////////////////////////////////
strPhone篩選后就是123