Re: Bypassing Interface Builder

FROM : I. Savant
DATE : Thu May 15 02:43:19 2008

Graham, your responses were very well-put. I had to step away from 
this thread to meet some deadlines today and I'm glad to see where 
it's gone for the most part. I rushed to the defense of IB because, 
for what it is intended, it really is a powerful and useful tool. 
Unnecessary struggle is silly, more so on a device designed to 
eliminate just that.

  Now to my point:

> You probably didn't mean what you wrote, but if you did, then you 
> would have had trouble - IB doesn't *ever* want you to do this. You 
> drag FROM outlet TO control. You drag FROM control TO target + 
> action method. It's always FROM source TO destination.


  I'd like to expand on this a bit. It's important to think of 
"messaging objects" here. In Objective-C we are supposed to refer to a 
method call as a "message".

[someObject performSomeAction];

  In this sense, we can easily visualize a "flow" of messages from a 
sender to a receiver. In Interface Builder, this concept is key to 
understanding the "connections" you establish by ctl-dragging from one 
object to another.

  The two types of connections Interface Builder allows serve two 
different purposes to achieve and/or facilitate this flow. An IBOutlet 
gives you the ability to name an object instance so you can send it 
messages by name. An IBAction allows you "codelessly" specify both the 
target and action of a control.

  In the case of IBOutlet, an example of this is creating a 
"nextButton" outlet in an AssistantWindowController object and 
connecting an instance of it to a "Next" button in an assistant window 
so that you can enable or disable the button (or change its title to 
"Finish") when certain things happen (of course you can use Bindings 
for this). In this case, the owner of the outlet wants to be the sender.

  In the case of an IBAction, an example is the -nextPage: method of 
an "AssistantWindowController". Connecting the button's action to the 
AssistantWindowController's -nextPage: method means that when the 
button's action is fired, that AssistantWindowCotroller instance 
receives the -nextPage: action with the next button as its sender. In 
this case the owner of the action wants to be the receiver.

  Interface Builder is just a GUI tool (in two senses) that lets you 
instantiate views and controllers and wire them up with names and 
actions mostly through drag-and-drop. Doing so entirely in code is 
ridiculously tedious by comparison.

--
I.S.