SwiftUI，无法从委托回调中更改状态？(附加代码)

import SwiftUI

struct ContentView: View {
    @State private var count = 0
    
    var body: some View {
        VStack {
            Text("Count: \(count)")
                .font(.largeTitle)
            
            Button(action: {
                self.incrementCount()
            }) {
                Text("Increment")
                    .font(.title)
                    .padding()
                    .background(Color.blue)
                    .foregroundColor(.white)
                    .cornerRadius(10)
            }
        }
    }
    
    func incrementCount() {
        count += 1
    }
}

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