Swiftui @EnvironmentObject update in View

Question

I am using an @EnvironmentObject (which is the ViewModel) and I have a demoData() function.

When I press it the data does change but my View is not updated.

How do I get the data to change in the View?

Thank you.

The view information:

import Combine
import SwiftUI

struct MainView: View {
 
    @EnvironmentObject var entry:EntryViewModel

     var body: some View {

         TextField("Beg Value", text: self.$entry.data.beg)
         TextField("Beg Value", text: self.$entry.data.end)

         Button(action: { self.entry.demoData() }) { Text("Demo Data") }

    }
}

ViewModel:

class EntryViewModel: ObservableObject {
 
    @Published  var data:EntryData = EntryData()

    func demoData() {
     
        var x = Int.random(in: 100000..<120000)
        x = Int((Double(x)/100).rounded()*100)
        data.beg = x.withCommas()
    
        x = Int.random(in: 100000..<120000)
       x = Int((Double(x)/100).rounded()*100)
       data.end = x.withCommas()
    
}

Model:

 EntryData:ObservableObject {

    @Published var beg:String = ""
    @Published var end:String = ""

}

pawello2222 · Accepted Answer · 2020-08-27 23:22:55Z

1

This is because EntryData is a class and if you change its properties it will still be the same object.

This @Published will only fire when you reassign the data property:

@Published var data: EntryData = EntryData()

A possible solution is to use a simple struct instead of an ObservableObject class:

struct EntryData {
    var beg: String = ""
    var end: String = ""
}

When a struct is changed, it's copied and therefore @Published will send objectWillChange.

answered Aug 27, 2020 at 23:22

pawello2222

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