How to create MVP and MVVM architecture in iOS Xcode project - ios

Question

I have read articles about MVC, MVP and MVVM architecture but I am not cleat about how to create each architecture in my iOS app. Which classes/controller files I need to use to make for each architecture. What is the difference between them if we are using with Storyboard/Xib/Programmatically?
As I am using Xcode default MVC structure for iOS apps but I want to create my new project with MVVM structure but I am not sure how to create that structure.
Any help would be highly appreciated.
Thanks in advance.

Answer 1

This is an oversimplification of the many variants of these design patterns, but this is how I like to think about the differences between the two.
MVC
MVP
MVVM
for more information you can look at here

Answer 2

MVVM architecture in iOS can be easily implemented without using third party dependencies. For data binding, we can use a simple combination of Closure and didSet to avoid third-party dependencies.
public final class Observable<Value> {
private var closure: ((Value) -> ())?
public var value: Value {
didSet { closure?(value) }
}
public init(_ value: Value) {
self.value = value
}
public func observe(_ closure: #escaping (Value) -> Void) {
self.closure = closure
closure(value)
}
}
An example of data binding from ViewController:
final class ExampleViewController: UIViewController {
private func bind(to viewModel: ViewModel) {
viewModel.items.observe(on: self) { [weak self] items in
self?.tableViewController?.items = items
// self?.tableViewController?.items = viewModel.items.value // This would be Momory leak. You can access viewModel only with self?.viewModel
}
// Or in one line:
viewModel.items.observe(on: self) { [weak self] in self?.tableViewController?.items = $0 }
}
override func viewDidLoad() {
super.viewDidLoad()
bind(to: viewModel)
viewModel.viewDidLoad()
}
}
protocol ViewModelInput {
func viewDidLoad()
}
protocol ViewModelOutput {
var items: Observable<[ItemViewModel]> { get }
}
protocol ViewModel: ViewModelInput, ViewModelOutput {}
final class DefaultViewModel: ViewModel {
let items: Observable<[ItemViewModel]> = Observable([])
// Implmentation details...
}
Later it can be replaced with SwiftUI and Combine (when a minimum iOS version in of your app is 13)
In this article, there is a more detailed description of MVVM
https://tech.olx.com/clean-architecture-and-mvvm-on-ios-c9d167d9f5b3

Answer 3

In MVVM, the View (which is really the UIViewController) asks the View Model for information.
textLabel.text = viewModel.textToShow
The view model has a representation of everything needed to construct the UI. The View asks the View Model for those values (like, what string to show).
In MVP, the Presenter tells the View what to do.
view.showText(textToShow)
The view controller implements a protocol that translates this request into view controller specifics:
func showText(_ text: String) {
textLabel.text = text
}
Here's an example of MVP: https://stackoverflow.com/a/54499119/246895.