Cannot assign to property: 'self' is immutable FIX it!

AllowChangeContentView.swift

//
//  AllowChangeContentView.swift
//  simpleSample
//
//  Created by ing.conti on 26/04/23.
//

/* You got: Cannot assign to property: 'self' is immutable

if You write;
struct ContentView: View {

    var msg = ""
...
 
 write SO:
 @State var msg = "" // CORRECT!
*/

import SwiftUI


struct ContentView: View {
    
    //var msg = ""      // WRONG! try to uncomment..
    @State var msg = "" // CORRECT!

    var body: some View {
        VStack {
            Text(msg)
            Button("Fill me!", action: {
                fillMe()
            })
        }
        .padding()
    }
    
    func fillMe(){
        self.msg = "Hello!!"
    }
}