#pragma mark - UITextView Delegate- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{ UITextRange *selectedRange = [textField markedTextRange]; //获取高亮部分 UITextPosition *pos = [textField 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 = [textField offsetFromPosition:textField.beginningOfDocument toPosition:selectedRange.start]; NSInteger endOffset = [textField offsetFromPosition:textField.beginningOfDocument toPosition:selectedRange.end]; NSRange offsetRange = NSMakeRange(startOffset, endOffset - startOffset); if (offsetRange.location < MAX_STARWORDS_LENGTH) { return YES; } else { return NO; } } NSString *comcatstr = [textField.text stringByReplacingCharactersInRange:range withString:string]; NSInteger caninputlen = MAX_STARWORDS_LENGTH - comcatstr.length; if (caninputlen >= 0) { return YES; } else { NSInteger len = string.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 = [string canBeConvertedToEncoding:NSASCIIStringEncoding]; if (asc) { s = [string 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 [string enumerateSubstringsInRange:NSMakeRange(0, [string length]) options:NSStringEnumerationByComposedCharacterSequences usingBlock: ^(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) [textField setText:[textField.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.lbNums.text = [NSString stringWithFormat:@"%d/%ld",0,(long)MAX_STARWORDS_LENGTH]; } return NO; }}// 计算转换后字符的个数- (NSUInteger) lenghtWithString:(NSString *)string{ NSUInteger len = string.length; // 汉字字符集 NSString * pattern = @"[\u4e00-\u9fa5]"; NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern options:NSRegularExpressionCaseInsensitive error:nil]; // 计算中文字符的个数 NSInteger numMatch = [regex numberOfMatchesInString:string options:NSMatchingReportProgress range:NSMakeRange(0, len)]; return len + numMatch;}#pragma mark - Notification Method-(void)textFieldDidChange:(UITextField *)textField{ UITextRange *selectedRange = [textField markedTextRange]; //获取高亮部分 UITextPosition *pos = [textField 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 = textField.text; NSInteger existTextNum = nsTextContent.length; if (existTextNum > MAX_STARWORDS_LENGTH) { //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_STARWORDS_LENGTH]; [textField setText:s]; } //不让显示负数 口口日 self.limitLabel.text = [NSString stringWithFormat:@"%lu",MAX(0,MAX_STARWORDS_LENGTH - textField.text.length)];}