I have seen both patterns where you have a view model for a view and you can either pass the view model in through the init of the view or have a configure method that takes in the view model and configures the property. What are the pros and cons for those patterns?

i.e.

struct ViewModel {
    let titleLabel: String
    let subtitleLabel: String
}

init method:

class View: UIView {
    let viewModel: ViewModel
    init(viewModel: viewModel) {
        self.viewModel = viewModel
    }
}

configure method:

class View: UIView {
    init() {}
    
    configure(viewModel: ViewModel) {
        // configuring view properties
    }
}

CodePudding user response：

Generally, if you can set properties of an object during from its initializer, it's preferable to do so, because you won't need the properties to be optional (or worse, have non-sense default values like 0 for ints, false for bools, etc.).

You also get the benefit of Swift's definite-initialization guarantees, which ensure that you can't forget to set any properties from the initializer. Contrast this with the configure(viewModel:) method, which you can forget to call.

However, there are times when this simply isn't possible, such as when using Storyboards (which initialize the views for you, without a chance for you to pass through any arguments to the initializer) or when you're building views that are meant to be recycled (such as cells in a table view).