iOS UiTextView限制输入字数的方法

pragma mark - textView代理方法

• (BOOL)textView:(UITextView )textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString )text{
  if ([text isEqualToString:@”\n”]) {
  [textView resignFirstResponder];//按回车取消第一相应者
  return NO;
  }
  return YES;
  }

• (BOOL)textViewShouldBeginEditing:(UITextView *)textView
  {
  提示Label.hidden = YES;//开始编辑时
  return YES;
  }

• (BOOL)textViewShouldEndEditing:(UITextView *)textView
  {//将要停止编辑(不是第一响应者时)
  if (textView.text.length == 0) {
  提示Label.hidden = NO;;
  }
  return YES;
  }

• (void)textViewDidChange:(UITextView *)textView
  {
  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;
  }

  NSUInteger count = textView.text.length;

  if (count > MAXVALUE) {

  NSRange rangeIndex = [textView.text rangeOfComposedCharacterSequenceAtIndex:MAXVALUE];
  if (rangeIndex.length == 1)
  {
      textView.text = [textView.text  substringToIndex:MAXVALUE];
  }
  else
  {
      NSRange rangeRange = [textView.text rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, MAXVALUE)];
      textView.text = [textView.text  substringWithRange:rangeRange];
  }
  [showMessage showWaring:[NSString stringWithFormat:@"字数不能多于%d个字", MAXVALUE]];
  _numberLabel.text = [NSString stringWithFormat:@"%ld/%ld", (long)MAXVALUE, (long)MAXVALUE];
  

  }
  else {
  _numberLabel.text = [NSString stringWithFormat:@”%ld/%ld”, (unsigned long)count, (long)MAXVALUE];
  }

}