What does IB mean in IBAction, IBOutlet, etc..?

Question

I am very new to iPhone development. I often encounter IBAction, IBOutlet and so on when reading Objective-C and Swift code. What does IB

Answer 1

IBAction and IBOutlet are interface Builder Constants IBOutlet:A Controller class can refer to the object in the nib file using a special constant called IBOutlet.

IBActions:Interface objects in the nib file can be set to trigger specific methods in controller class using IBAction as return type of the method.

Answer 2

"Interface Builder".

Before Xcode 4, the interface files (XIBs and NIBs) were edited in a separate program called Interface Builder, hence the prefix.

IBAction is defined to void, and IBOutlet to nothing. They are just clues to Interface Builder when parsing files to make them available for connections.

Just to add the reference, inside AppKit/NSNibDeclarations.h you'll find these:

#ifndef IBOutlet
#define IBOutlet
#endif

#ifndef IBAction
#define IBAction void
#endif

So, actually, code like this:

@interface ...
{
    IBOutlet NSTextField *label;
}
- (IBAction)buttonPressed:(id)sender;
@end

Will be transformed into:

@interface ...
{
     NSTextField *label;
}
- (void)buttonPressed:(id)sender;
@end

By the preprocessor, even before the compiler sees it. Those keywords were acting just as clues to Interface Builder.

Answer 3

IB stands for interface builder, as you connect objects via the interface builder .