NSCharacterSet 简单用法

NSMutableCharacterSet *base = [NSMutableCharacterSet lowercaseLetterCharacterSet]; //字母
  NSCharacterSet *decimalDigit = [NSCharacterSet decimalDigitCharacterSet];   //十进制数字
  [base formUnionWithCharacterSet:decimalDigit];    //字母加十进制
  NSString *string = @"ax@d5s#@sfn$5`SF$$%x^(#e{]e";
  //用上面的base隔开string然后组成一个数组，然后通过componentsJoinedByString，来连接成一个字符串
  NSLog(@"%@",[[string componentsSeparatedByCharactersInSet:base] componentsJoinedByString:@"-"]);
  [base invert];  //非 字母加十进制
  NSLog(@"%@",[[string componentsSeparatedByCharactersInSet:base] componentsJoinedByString:@"-"]);

- (BOOL)isPureNumandCharacters:(NSString *)string
{
    string = [string stringByTrimmingCharactersInSet:[NSCharacterSet decimalDigitCharacterSet]];
    if(string.length > 0)
    {
        return NO;
    }
    return YES;
}