一、设置UITextView的delegate为控制器
二、实现代理方法
#pragma mark - UITextViewDelegate - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range
replacementText:(NSString *)text
{
UITextRange *selectedRange1 = [textView markedTextRange];
//获取高亮部分
UITextPosition *pos = [textView positionFromPosition:selectedRange1.start offset:];
//获取高亮部分内容
//NSString * selectedtext = [textView textInRange:selectedRange]; //如果有高亮且当前字数开始位置小于最大限制时允许输入
if (selectedRange1 && pos) {
NSInteger startOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange1.start];
NSInteger endOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange1.end];
NSRange offsetRange = NSMakeRange(startOffset, endOffset - startOffset); if (offsetRange.location < MAX_LIMIT_NUMS) {
return YES;
}
else
{
return NO;
}
} NSString *comcatstr = [textView.text stringByReplacingCharactersInRange:range withString:text]; // NSInteger caninputlen = MAX_LIMIT_NUMS - comcatstr.length;
NSInteger caninputlen = MAX_LIMIT_NUMS - [comcatstr getStringLengthIfIsEmojiLengthAsOne]; if (caninputlen >= )
{
return YES;
}
else
{
// NSInteger len = text.length + caninputlen;
NSInteger len = [text getStringLengthIfIsEmojiLengthAsOne] + caninputlen; //防止当text.length + caninputlen < 0时，使得rg.length为一个非法最大正数出错
NSRange rg = {,MAX(len,)}; if (rg.length > )
{
NSString *s = @"";
//判断是否只普通的字符或asc码(对于中文和表情返回NO)
BOOL asc = [text canBeConvertedToEncoding:NSASCIIStringEncoding];
if (asc) {
s = [text substringWithRange:rg];//因为是ascii码直接取就可以了不会错
}
else
{
__block NSInteger idx = ;
__block NSString *trimString = @"";//截取出的字串
//使用字符串遍历，这个方法能准确知道每个emoji是占一个unicode还是两个
[text enumerateSubstringsInRange:NSMakeRange(, [text length])
options:NSStringEnumerationByComposedCharacterSequences
usingBlock: ^(NSString* substring, NSRange substringRange, NSRange enclosingRange, BOOL* stop) {
// NSInteger steplen = substring.length;
NSInteger steplen = [substring getStringLengthIfIsEmojiLengthAsOne]; if (idx >= rg.length) {
*stop = YES; //取出所需要就break，提高效率
return ;
} trimString = [trimString stringByAppendingString:substring]; idx = idx + steplen;
}]; s = trimString;
} __block BOOL hasAttachment = NO;
[textView.attributedText enumerateAttributesInRange:NSMakeRange(, textView.attributedText.length) options:NSAttributedStringEnumerationReverse usingBlock:^(NSDictionary *attrs, NSRange range, BOOL *stop) { if(attrs[@"NSAttachment"])
{
*stop = YES;
hasAttachment = YES;
}
}]; if (textView.text.length > MAX_LIMIT_NUMS) {
[self showHudTipStr:@"输入已达上限"];
if (hasAttachment) { [textView.attributedText attributedSubstringFromRange:NSMakeRange(, MAX_LIMIT_NUMS)]; } else { //rang是指从当前光标处进行替换处理(注意如果执行此句后面返回的是YES会触发didchange事件)
[textView setText:[textView.text stringByReplacingCharactersInRange:range withString:s]];
}
} //既然是超出部分截取了，哪一定是最大限制了。
self.inputNumberTipsLabel.text = [NSString stringWithFormat:@"%d/%ld",,(long)MAX_LIMIT_NUMS];
}
if (textView.text.length >= MAX_LIMIT_NUMS) {
[self showHudTipStr:@"输入已达上限"];
}
return NO;
} } - (void)textViewDidChange:(UITextView *)textView
{
// 占位文本显示与否
// _submitEvaluationBtn.enabled = self.evaluationTextView.hasText; UITextRange *selectedRange1 = [textView markedTextRange];
//获取高亮部分
UITextPosition *pos = [textView positionFromPosition:selectedRange1.start offset:]; //如果在变化中是高亮部分在变，就不要计算字符了
if (selectedRange1 && pos) {
return;
} NSString *nsTextContent = textView.text;
// NSInteger existTextNum = nsTextContent.length;
NSInteger existTextNum = [nsTextContent getStringLengthIfIsEmojiLengthAsOne]; if (existTextNum >= MAX_LIMIT_NUMS)
{
[self showHudTipStr:@"输入已达上限"];
__block BOOL hasAttachment = NO;
[textView.attributedText enumerateAttributesInRange:NSMakeRange(, textView.attributedText.length) options:NSAttributedStringEnumerationReverse usingBlock:^(NSDictionary *attrs, NSRange range, BOOL *stop) { if(attrs[@"NSAttachment"])
{
*stop = YES;
hasAttachment = YES;
}
}]; if (hasAttachment) { textView.attributedText = [textView.attributedText attributedSubstringFromRange:NSMakeRange(, MAX_LIMIT_NUMS + [textView.text emojiCount])]; } else {
//截取到最大位置的字符(由于超出截部分在should时被处理了所在这里这了提高效率不再判断)
NSString *s = [nsTextContent substringToIndex:(MAX_LIMIT_NUMS + [textView.text emojiCount])]; [textView setText:s];
}
} //不让显示负数 口口日
self.inputNumberTipsLabel.text = [NSString stringWithFormat:@"%tu/%tu",MAX(,MAX_LIMIT_NUMS - existTextNum),MAX_LIMIT_NUMS];
}