FWIW, my experience is almost exactly opposite. There’s not enough architecture in the iOS world. The norm is to stitch together the app without clear notion of the state or its transitions, everything is hidden in a giant tangle of view controllers, a lot of the state is crammed into the app delegate singleton, everything calls everything else via singletons and good luck finding the UI flow in a web of storyboards where arguments are passed in prepareForSegue. It’s a huge mess.

Talking about target-action or delegation in this context is IMHO a misunderstanding. These are very nice and valid solutions, but in my experience they are simply not enough to build a structured non-trivial app with. They are the basic building blocks, but there has to be something above them.

Of course, it’s also a mistake to go overboard with structure, drowning the important bits in architecture boilerplate. Architecture cannot and must not be followed blindly, as a cooking book. You have to aim for a reasonable compromise, a point of diminishing returns.