MVVM Is Not Very Good
Nobody has any idea what the words “view model” mean, and so they can’t agree on what to put in them. The concept itself is too abstract. None of these writers would disagree about what goes in a Validator class, or a Presenter class, or a Fetcher class, and so on. Those are all better names with tightly defined roles.
Giving the same name to a wide variety of different objects with drastically different responsibilities only serves to confuse readers. If we can’t agree view models should do, what’s the benefit to giving them all the same name?
Update (2015-12-21): Ash Furrow (comments):
Next, does MVVM encourage objects that have many responsibilities? Sure, I guess it does. But again, the alternative that most iOS developers are familiar with is a massive view controller. So compared to MVC, MVVM is just telling you to use objects with one fewer responsibilities, which is a step in the right direction!
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I argue that moving to MVVM (keeping the existing app structure, plus view models) is still a great idea. Separating as much code from the view layer as possible makes it way easier to further factor those components into smaller-yet objects.
Both articles, I think, are really arguing the same things, but maybe from different directions[…]
