SwiftUI: prevent View from refreshing when presenting a sheet

It needs to make separated condition-independent view to achieve behavior as you wish, like below

struct RandomView: View {
    var body: some View {
        Text("Random text: \(Int.random(in: 0...100))")
    }
}

struct ContentView: View {

    @State var active = false

    var body: some View {
        VStack {
            RandomView()

            Button(action: { self.active.toggle() }) {
                Text("Show pop up")
            }
        }
        .sheet(isPresented: $active) {
            Text("POP UP")
        }
    }
}

In this case RandomView is not rebuilt because is not dependent on active state.

Asperi sad :

View is struct, value type, if any part of it changed then entire value changed

He is absolutely right! But for that we have state properties. When the view is recreated, the value of state doesn't change.

This should work, as you expected

struct ContentView: View {

    @State var active = false
    @State var number = Int.random(in: 0 ... 100)
    var body: some View {
        VStack {
            Text("Random text: \(number)")

            Button(action: { self.active.toggle() }) {
                Text("Show pop up")
            }
        }
        .sheet(isPresented: $active) {
            Text("POP UP")
        }
    }
}

What is the advantage? For simple things, the state / binding is the best solution, without any doubt.

import SwiftUI

struct SheetView: View {
    @Binding var randomnumber: Int
    var body: some View {
        Button(action: {
            self.randomnumber = Int.random(in: 0 ... 100)
        }) {
            Text("Generate new random number")
        }
    }
}
struct ContentView: View {

    @State var active = false
    @State var number = Int.random(in: 0 ... 100)
    var body: some View {
        VStack {
            Text("Random text: \(number)")

            Button(action: { self.active.toggle() }) {
                Text("Show pop up")
            }
        }
        .sheet(isPresented: $active) {
            SheetView(randomnumber: self.$number)
        }
    }
}
struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Now you can dismiss the sheet with or without generating new random number. No external model is required ...