When is 'drawRect' called?

Question

I have some custom drawing code in drawRect which also performs some calculation of sizes.

When is the earliest I can be sure that this code has been loaded, e.g. if I want to modify it's containers size accordingly?

Answer 1

I have some custom drawing code in drawRect which also performs some calculation of sizes.

When is the earliest I can be sure that this code has been loaded, e.g. if I want to modify it's containers size accordingly?

An object can't exist until its class is fully loaded. If you have an instance, the class that it's an instance of is completely loaded, because you wouldn't have an instance of it if it wasn't.

As for when it's called: It's called when you need to draw. This normally happens as part of the event loop, if anything has marked the view as needing display. It is possible to directly tell an NSView to display, but, as far as I can tell, this is not possible for UIViews.

So, if you need to do something to it before it gets told to, either do it immediately after creating it or, if you're about to set the view as needing display, do it before you do that.

Answer 2

-[NSView viewWillDraw] is a reasonable place for last minute layout.