First example for @State property wrapper.

ContentView.swift

import SwiftUI

struct ContentView: View {
    
    @State private var infoString : String?
    
    var body: some View {
        VStack {
            Text(infoString ?? "No name")
            Button("Change text") {
                infoString = "Giray"
            }
        }
    }
    
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}