限制textView输入字数限制textView输入字数

1、简单限制输入长度
先看下效果

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#pragma mark UITextView Delegate限制输入最大长度 -(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text { #define MY_MAX 30 if ([text isEqualToString:@""] && range.length > 0) { //删除字符肯定是安全的 return YES; }else { if (textView.text.length - range.length + text.length > MY_MAX) { [self showAlertView:@"超出最大可输入长度"]; return NO; } else { return YES; } } }

- (void)showAlertView:(NSString *)message{ UIAlertController *alertController = [UIAlertController alertControllerWithTitle:nil message:message preferredStyle:UIAlertControllerStyleAlert]; UIAlertAction *sure = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleCancel handler:nil]; [alertController addAction:sure]; [self presentViewController:alertController animated:YES completion:nil]; }

【限制textView输入字数】2、限制输入长度，并动态计算可输入字数

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![4A6D149B-7718-4D2B-80DC-F47D78C2F95E.png](http://upload-images.jianshu.io/upload_images/2988670-706e3b64d3af337e.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

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#pragma mark UITextView Delegate限制输入最大长度 -(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text { #define MY_MAX 10 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 < MY_MAX) { return YES; } else { return NO; } } NSString *comcatstr = [textView.text stringByReplacingCharactersInRange:range withString:text]; NSInteger caninputlen = MY_MAX - 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: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) [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.textLength.text = [NSString stringWithFormat:@"%d/%ld",0,(long)MY_MAX]; } return NO; } }

-(void)textViewDidChange:(UITextView *)textView { if (textView.text.length > 0) { self.cancleBtn.hidden = NO; }else{ self.cancleBtn.hidden = YES; } UITextRange *selectedRange = [textView markedTextRange]; //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 > MY_MAX) { //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:MY_MAX]; [textView setText:s]; } //不让显示负数口口日 self.textLength.text = [NSString stringWithFormat:@"%ld/%d",MAX(0,MY_MAX - existTextNum),MY_MAX]; }