iOS MVVM with POP

ios_mvvm_pop.playground

//: Playground - noun: a place where people can play

import UIKit



protocol PaginatedDataStateProtocol {
    var items: [NSObject] { get set }
    var page: Int { get set }
    var isFetching: Bool { get set }
}




protocol PaginatedDataViewModelProtocol {
    associatedtype DataStateType
    var state: DataStateType { get set }

    mutating func onLoadFirstDataPage()
    mutating func onLoadNextDataPage()
    func checkLoadNextPage()
}

extension PaginatedDataViewModelProtocol  {
    mutating func onLoadFirstDataPage() {
        var updState = self.state as! PaginatedDataStateProtocol
        updState.page = 1
        updState.isFetching = true
        self.state = updState as! DataStateType
    }
    mutating func onLoadNextDataPage() {
        
    }
    func checkLoadNextPage() {
    }
}



// Model
struct CityModel {}

// ViewModel State
struct SelectCityState: PaginatedDataStateProtocol {
    var items: [NSObject]
    var page: Int
    var isFetching: Bool

    var selected: NSObject?
    var search: String?
}

// ViewModel
struct SelectCityViewModel: PaginatedDataViewModelProtocol {
    var state: SelectCityState

    init() {
        self.state = SelectCityState(items: [], page: 0, isFetching: false, selected: nil, search: nil)
    }
}

// View
class ViewController {
    var viewModel: SelectCityViewModel! {
        didSet {
            self.updateView()
        }
    }

    func onClick() {
        self.viewModel.onLoadFirstDataPage()
    }

    private func updateView() {
        print(".ViewController.update", self.viewModel.state)
    }
}

var vm = SelectCityViewModel()
let vc = ViewController()
vc.viewModel = vm


vc.onClick()