When building iPhone applications that support or provide text input, it’s often necessary to create some extra buttons (or other controls) beyond the ones provided by the default keyboard interface. Those buttons should be created for specific operations needed by your application, such as moving to the next or previous text field, make the keyboard disappear e.t.c. To understand what exactly this is all about, just see what’s happening when you are using the Safari browser and you type username/password values to login in your e-mail account. Just right above the keyboard, there are two buttons that allow you to move to the next or previous field and a third button that allows you to close the keyboard and see the whole browser again.
That area above the keyboard is an extra UIView, known as Input Accessory View. That view is supported by the UITextField and UITextView as well and is added to any control of that kind using the setInputAccessoryView method. But that’s the last step. All the controls existsing in the Input Accessory View must be created prior to adding the view to the textfield/textview.