viewWillAppear versus loadView for building view hierarchy

I'm constructing my view hiera开发者_运维问答rchy through code and would like to know if it's better to create the entire hierarchy in loadView, when the view is requested from my controller, and then animate the views onto the screen in the viewWillAppear method, or if it's better to keep things simpler but potentially require more freeing and allocating of memory by building the entire hierarchy in viewWillAppear.

My understanding is that the controller calls loadView to create the view the first time it needs it, then keeps it around as long as it can so that you can leave and return to this controller and animate in the views, but not need to recreate and attach them, via viewWillAppear.

Basically, I'm finding it messy to be separately allocating the views in loadView and then transitioning (and sometimes updating the contents within) them in viewWillAppear, and wondering if the benefits of retaining the views don't outweigh the simplicity of simply recreating them (and consequently re-initializing them and avoiding any un-reset values).

loadView is called only once at the creation and should contation everithing to create the view.

viewWillAppear:(BOOL)animated is called everytime the view is displayed. If your view was retained, you can update/set your data in this. (Your UIButtons, UILabels,... are already allocated by loadView, you just set the content here.)