iOS基于UITextView的字数限制和输入量显示

本文主要是介绍iOS基于UITextView的字数限制和输入量显示，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

#define MAX_LIMIT_NUMS 50
//显示输入字数和限制数_textNumLab = [[UILabel alloc] init];_textNumLab.font = GetFont(FONT_BUTTON);_textNumLab.text = @"0/50";_textNumLab.textAlignment = 2;[self addSubview:_textNumLab];#pragma mark -限制病情描述输入字数(最多不超过MAX_LIMIT_NUMS个字)
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{//不支持系统表情的输入if ([[textView textInputMode]primaryLanguage]==nil||[[[textView textInputMode]primaryLanguage]isEqualToString:@"emoji"]) {return NO;}UITextRange *selectedRange = [textView markedTextRange];//获取高亮部分UITextPosition *pos = [textView positionFromPosition:selectedRange.start offset:0];//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 (selectedRange && pos) {NSInteger startOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.start];NSInteger endOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.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;if (caninputlen >=0){return YES;}else{NSInteger len = text.length + 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 = {0,MAX(len,0)};if (rg.length >0){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 =0;__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(0, [text length])options:NSStringEnumerationByComposedCharacterSequencesusingBlock: ^(NSString* substring,NSRange substringRange,NSRange enclosingRange,BOOL* stop) {if (idx >= rg.length) {*stop =YES;//取出所需要就break，提高效率return ;}trimString = [trimString stringByAppendingString:substring];idx++;}];s = trimString;}//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。_textNumLab.text = [NSString stringWithFormat:@"%d/%ld",0,(long)MAX_LIMIT_NUMS];}return NO;}
}#pragma mark -显示当前可输入字数/总字数
- (void)textViewDidChange:(UITextView *)textView{UITextRange *selectedRange = [textView markedTextRange];if (_delegate && [_delegate respondsToSelector:@selector(didChangeValue:cell:)]) {[_delegate didChangeValue:textView.text cell:self];}//获取高亮部分UITextPosition *pos = [textView positionFromPosition:selectedRange.start offset:0];//如果在变化中是高亮部分在变，就不要计算字符了if (selectedRange && pos) {return;}NSString  *nsTextContent = textView.text;NSInteger existTextNum = nsTextContent.length;if (existTextNum >MAX_LIMIT_NUMS){//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 setText:s];}//    //不让显示负数(倒计数)
//    _textNumLab.text = [NSString stringWithFormat:@"%ld/%d",MAX(0,MAX_LIMIT_NUMS - existTextNum),MAX_LIMIT_NUMS];
//正向计数_textNumLab.text = [NSString stringWithFormat:@"%ld/%d",MIN(50,existTextNum),MAX_LIMIT_NUMS];
}