UITextView 200字符限制，中文算1个字，英文算0.5个字

//注册监听方法

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewChanged:) name:UITextViewTextDidChangeNotification object:self.replyTextView];

/**

 *  计算输入的字数,超出规定字数不允许输入

 *

 *  @param noti 通知

 */

- (void)textViewChanged:(NSNotification *)noti

{

    NSString * textContent = self.replyTextView.text;

    int existTextNum = [textContent lengthForCString];;

   

    NSString *language = [self.replyTextView.textInputMode primaryLanguage];

   

    if ([language isEqualToString:@"zh-Hans"])
{

        //中文

        UITextRange * selectedRange = [self.replyTextView markedTextRange];

        UITextPosition * position = [self.replyTextView positionFromPosition:selectedRange.start offset:0];

       

        if (!position) {

            //没有选中字符

           

            if (existTextNum > TextViewMaxLength)
{

                //大于200字符

                textContent = [textContent subStringWithByteLength:TextViewMaxLength];

                existTextNum = TextViewMaxLength;

                self.replyTextView.text =
textContent;

            }else

            {

                //小于200字符
//                existTextNum = [textContent lengthForCString];

            }

        }else

        {

            //有选中字符
//            existTextNum = [textContent lengthForCString];

        }

    }else

    {

        //英文

//        existTextNum = [textContent lengthForCString];

if (existTextNum > TextViewMaxLength)

{

            //大于200字符

            textContent = [textContent subStringWithByteLength:TextViewMaxLength];

            existTextNum = TextViewMaxLength;

            self.replyTextView.text =
textContent;

}

    }

   

    self.currentCountLabel.text =
[NSString stringWithFormat:@"%d",
existTextNum];

}

//下面这两个个都是分类里的方法，写个NSString的分类放里面用就可以了。

//这个方法从网上找的。

/**

 *  计算字符串字节长度,中文一个字节，英文0.5字节

 *

 *  @return 字节长度

 */

- (int)lengthForCString

{

    int strlength = 0;

    char * p = (char *)[self cStringUsingEncoding:NSUnicodeStringEncoding];

    for (int i
= 0; i < [self lengthOfBytesUsingEncoding:NSUnicodeStringEncoding];
i ++) {
//        NSLog(@"*p:%c",*p);

        if (* p) {

            p ++;

            strlength ++;

        }

        else {

            p ++;

        }

    }

    return (strlength + 1)/2;

}

//这个是自己写的。

/**

 *  按字节数截取字符串，中文一个字节，英文0.5字节，如果最后字符是半个中文，自动抛掉最后一个字符

 *

 *  @param length 字节数

 *

 *  @return 截取后的字符串

 */

- (NSString *)subStringWithByteLength:(int)length

{

    float bytesCount = 0;

    float lastBytesCount = 0;

    for (int i
= 1; i <= self.length;
i ++) {

       

        //        NSLog(@"byteLength:%ld", [[self substringWithRange:NSMakeRange(i - 1, 1)] lengthOfBytesUsingEncoding:NSUTF8StringEncoding]);

       

        if ([[self substringWithRange:NSMakeRange(i
- 1, 1)] lengthOfBytesUsingEncoding:NSUTF8StringEncoding]
== 3) {

            bytesCount ++;

        }else

        {

            bytesCount += 0.5;

        }

       

        if (bytesCount > length) {

            //            NSLog(@"byteCount:%f", lastBytesCount);

            return [self substringWithRange:NSMakeRange(0,
i - 1)];

        }else if (bytesCount == length)

        {

            return [self substringWithRange:NSMakeRange(0,
i)];

        }else

        {

            lastBytesCount = bytesCount;

        }

    }

    return @"按字节截取字符串出错，请检查截取字节是否超出范围。";

}