How to disable Go button on iPhone keyboard

Can any one please let me kno开发者_高级运维w how to disable the 'Go' button on keyboard?

The purpose is: when the text field is empty Go button has to be disable (gray color) and when type some thing the Go button become active and color blue. (Same as Apple Find iPhone app).

Many thanks

In Interface builder, tick the box which is labelled Auto-enable Return Key.

In code do: [textField setEnablesReturnKeyAutomatically:YES];

The Return key (Go key) will only be enabled when the text field is not empty.