ios textView 限制输入的最大长度

- (void)textViewDidChange:(UITextView *)textView
{
UILabel *countLabel = [self.view viewWithTag:999];
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;
}
countLabel.text = [NSString stringWithFormat:@"%lu/200", (unsigned long)textView.text.length];
if ( (unsigned long)textView.text.length > 200) {
// 对超出的部分进行剪切
textView.text = [textView.text substringToIndex:200];
countLabel.text = @"200/200";
     }
}