Understanding @StateObject in SwiftUI for iOS 14

切换注释的地方，就知道效果了

import SwiftUI

class Counter: ObservableObject {
    @Published var count : Int = 0
}

struct CounterView: View {
//    @ObservedObject var counter = Counter()
    @StateObject var counter = Counter()
    
    var body: some View {
        VStack {
            Text("CounterView count number")
            Text("\(counter.count)")
            Button("Increment CounterView count") {
                counter.count += 1
            }
        }.padding()
        .background(Color.red)
    }
}

struct ContentView: View {
    @State private var value = 0
    var body: some View {
        VStack {
            Text("ContentView value number")
            Text("\(value)")
            Button("Increment ContentView value") {
                value += 1
            }
            CounterView()
        }.padding()
        .background(Color.green)
    }
}

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

配合文章以及视频 效果更佳

@StateObject 和 @ObservedObject 的区别和使用

Understanding @StateObject in SwiftUI for iOS 14