swiftui 状态变量计数丢失了它存储的内容 [英] swiftui state variable count lost what it stored

问题描述

当我点击 onTapGesture 事件进行设置时

when I click onTapGesture event to setup

  self.showDetailView = true
  self.count = 5

工作表会弹出，但self.count总是0，而不是5.所以代码 Text("5555") 永远不会被命中.

the sheet will popup, but the self.count always be 0, not be 5. so the code Text("5555") will never be hitt.

状态变量 count 似乎丢失了它存储的内容.

it seems state variable count lost what it stored.

import SwiftUI

struct ContentView: View {
    @State var showDetailView = false
    @State var count = 0
    var testArr = [1,2,3,4,5]
    var body: some View {
        
        NavigationView {
            List(testArr.indices){ indice in
                Text("row num \(indice)")
                    .onTapGesture{
                        
                        self.showDetailView = true
                        self.count = 5
                        }
                
                }
                .sheet(isPresented: self.$showDetailView) {
                    if self.count == 0{
                        //  print("count = 0")
                    }
                    if  self.count == 5{
                        Text("5555")
                    }
                
                }
            
                .navigationBarTitle("Your Reading")
        }
        }
    }

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

推荐答案

另一种方法是:

class CountModel: ObservableObject {
  @Published var count: Int = 0
    init(_ c: Int) { self.count = c }
}

struct ContentView: View {

@State var showDetailView = false
@ObservedObject var model = CountModel(0)
var testArr = [1,2,3,4,5]

var body: some View {
    NavigationView {
        List(testArr.indices) { indice in
            Text("row num \(indice)")
                .onTapGesture {
                    self.model.count = 5
                    self.showDetailView = true
                }
        }
        .sheet(isPresented: self.$showDetailView) {
            if self.model.count == 0 {
                let _ = print("count = 0")
                Text("0000")
            }
            if self.model.count == 5 {
                let _ = print("count = 5")
                Text("5555")
            }
        }
        .navigationBarTitle("Your Reading")
    }
}

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