Lets you make a graphic user interface using graphic tools. It takes some getting used to, but once you "get it", it's invaluable. It's best understood by working through an example. But a bit of background preparation may help:
To use Interface Builder, you create an "Interface Builder Custom Object" and configure a user interface to send messages to an instance of your object.
There is one big restriction on Custom Objects: Any method that is invoked from the user interface must have exactly one argument and this argument must be the control that sent the message. Example:
- setFreq: sender
{
freq = [sender doubleValue];
}
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You can also send messages directly to the interface from within your Custom Object. To do this, you need to know the id of the controls in your interface. Interface Builder provides a mechanism called "outlets" to do this. Outlets are simply id-valued instance variables defined by your Custom Object. In Interface Builder, you can connect an outlet to a control―then, when your program runs, the instance variable's value will be the control and you can send whatever messages you like to it.