Show a hint in a text field to help communicate purpose.A text field can contain placeholder text—such as "Email" or "Password"—when there’s no other text in the field. Don’t use a separate label to describe a text field when placeholder text is sufficient.
那么常常在设计表单的时候，会碰到一个问题：输入项到底是采用label+textfield(with placeholder)，还是说采用table cell进入子页面进行textfield(with or without placeholder)输入获取数据后返回好。
