How do I pass a value to a ViewModel from a View using the .environmentObject() in Swift?-CodePudding

I have created a ViewModel with an init() that accepts a parameter something like this. PS: Learning swift and swiftUI

//UsersViewModel.swift
class UsersViewModel: ObservableObject {
  @Published var users: [User]
  @Published var category: String
  init(category: String) {
    self.category = continentcategory
    self.users = UserData().getUsers(byCategory: category)
  }
}

UserData is the Data Model where I have a function getUsers(byCategory) that allows me to get a subset of data instead of all data and then filtering it.

For my SwiftUI view

//UserListByCategory.swift

import SwiftUI
struct UserListByCategory: View {
    @EnvironmentObject var ud: UsersViewModel
    var body: some View {
        Text("Hello")
    }
}

struct UserListByCategory_Previews: PreviewProvider {
    static var previews: some View {
        UserListByCategory()
            .environmentObject(UsersViewModel(category: "Office"))
    }
}

This above SwiftUI View gets called by another ListView after the user selects a category. How do I pass that category without hardcoding it here?

CodePudding user response：

In SwiftUI we don't use view model objects for our view data. View structs are our primary encapsulation mechanism, e.g.

If you need to fetch your data:

struct UserListByCategory: View {

    let category: String
    @State var users: [User] = []

    var body: some View {
        List {
            ForEach(users) { user in
                Text("\(user.name)")
            }
        }
        .task(id: category) {
            users = await fetchUsers(category: category)
        }
    }
}

struct UserListByCategory_Previews: PreviewProvider {
    static var previews: some View {
        UserListByCategory(category: "Office")
    }
}

If you already have all the model data, pass it down the View struct hierarchy as follows:

struct ContentView: View {
    @ObservedObject var model: Model
    var body: some View {
        UserList(users: model.users(category:"Office"))
    }
}

struct UserList: View {
    let users: [User]

    var body: some View {
        List {
            ForEach(users) { user in
                Text("\(user.name)")
            }
        }
    }
}

CodePudding user response：

The answer was to create a ViewModelFactory This link https://mokacoding.com/blog/swiftui-dependency-injection/#view-models-view-model-factory was extremely helpful in setting up my app with ViewModels for each View and set up a Factory that allowed me for navigation and do Dependency Injections.