2019-01-29

    UILabel *placeHolderLabel = [[UILabel alloc] init];
    placeHolderLabel.text = @"写笔记...";
    placeHolderLabel.numberOfLines = 0;
    placeHolderLabel.textColor = [UIColor lightGrayColor];
    [placeHolderLabel sizeToFit];
    [self.textView addSubview:placeHolderLabel];