NSCharacterSet笔记

NSCharacterSet
表示用于搜索操作的一组固定Unicode字符值的对象。

字符串处理的例子

    NSString *string = @"1212erd35446dfd456";
    NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"erdf"];
    NSArray *setArray = [string componentsSeparatedByCharactersInSet:characterSet];
    NSString *resultString = [setArray componentsJoinedByString:@""];

输出：121235446456

 + controlCharacterSet
 + whitespaceCharacterSet              //空格
 + whitespaceAndNewlineCharacterSet    //空格和换行符
 + decimalDigitCharacterSet            //0-9的数字
 + letterCharacterSet                  //所有字母
 + lowercaseLetterCharacterSet         //小写字母
 + uppercaseLetterCharacterSet         //大写字母
 + alphanumericCharacterSet            //所有数字和字母（大小写不分）
 + punctuationCharacterSet             //标点符号
 + newlineCharacterSet                 //换行

textfield只可以输入数字

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    NSCharacterSet *charSet = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789"]  invertedSet];
    NSString *str = [[string componentsSeparatedByCharactersInSet:charSet] componentsJoinedByString:@""];
    if ([string isEqualToString:str])
   {
        return YES;
    }
    else
    {
        return NO;
     }
}