iPhone - UIView adding a subView vs drawRect?

Question

What are the differences between adding a view as a subView VS drawing the view in that view's drawRect method?.

I use both approaches, but I was wondering apart from the obvious such as, if you do in drawRect it will be a single View, as opposed as two views, or adding as a subview is just easier. Are there any specific situations where you should definitely use one over the other?

Answer 1

Overriding -drawRect: can be a good way to draw complex UITableViewCell s. Having all of the subviews composited and drawn as one view helps table view scrolling performance immeasurably.

Having said that, I typically stick with the highest level API available and drop down to a lower level only if performance suffers.

Answer 2

Adding a subview is easier as you point out, and I really see this as no contest in 90% of cases. You should generally add a subview and let the libraries handle drawing of subviews in their correct position.

I only use -drawRect: to accomplish custom drawing within my view, but not to draw subviews, it creates unnecessary complexity. If you need a lot of performance, -drawRect: can help you there. Also, in the case of simple drawing, -drawRect: is very nice as opposed to making several subviews. But in general, it pays to just add a subview.

If in the future you decide you want these subviews to receive touch events or handle things interactively, it is more difficult to refactor your -drawRect: code.