A while ago I became a fan of creating/manipulating the view hierarchy through code. Both because I think is more expressive and forces me to learn more about Cocoa.
But I just wrote a 5 lines of code which would look way more expressive if an IBOulet was used. It finds a subview within a view with a specific tag and sends a message to it. But I could easily create an IBOutlet and do it in one line only.
Because of this, I ask: is creating an IBOutlet too expensive?
P.S.: Let's cut off the "readability over performance" for now. I really want to know the impact of this.
IBOutlet is a marker for Xcode that gets removed by the time the preprocessing step is over. Internally, setting it up boils down to assigning a single pointer to an instance variable that "backs" the IBOutlet property. This pointer is assigned at the time the view is set up, and does not change after that. It is very cheap.
Finding a subview by tag, on the other hand, is a run-time operation that needs to run every time that you are looking for the subview. Usually it is cheap, but it may become considerably more expensive in a view with large number of subviews that have subviews as well.
Therefore, I would definitely go for IBOutlet, because it's a one-time deal, and because it lets you shorten the code from five lines to one.