Responding to a button tap
In this section, we will begin making a view responsive by examining the simplest case; that is, building a view that needs to respond to a simple user event, a button tap, and changing the view appearance in response.
Let’s start by trying to write the first thing that would intuitively come to mind; let’s change a variable’s value and have the view respond to that value change, as shown in the following code example:
import SwiftUI
struct MyViewStruct: View {
    var name = "Mary"
    var body: some View {
        VStack(spacing: 20) {
            Text("Variables in structs are immutable")
                .fontWeight(.heavy)
           ... 
                                             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
     
         
                 
                 
                 
                 
                 
                 
                 
                 
                