So far, we have done a great job in preventing user error. Each interface object has specific input associated with it. When a user clicks on the 7 button, for example, only a 7 can be entered into our equation. What if you gave the user access to the keyboard? That would introduce a wide range of possible data input errors. In this section, we'll delve into the area of validating user input.
Our Mobile Calculator application only has one card. Let's get started by naming that card
Basic. Next, we'll create a new card and name it
Advanced. Next, follow these steps to set up the user interface on the Advanced card.