SwiftUI 列表正在工作，但选择器不起作用

Posted 2023-02-24

【中文标题】SwiftUI 列表正在工作，但选择器不起作用

【英文标题】：SwiftUI List is working but not the picker

【发布时间】：2020-07-26 15:42:59

【问题描述】：

我有这个看法。该列表通过显示数据可以正常工作。选择器不工作。它不显示任何数据。两者都使用相同的对象和功能。我不知道选择器不显示数据的原因。我想使用选择器。我放置列表只是为了尝试确定问题，但我仍然不知道。

 import SwiftUI

struct GameListPicker: View 

@ObservedObject var gameListViewModel = GameListViewModel()
@State private var selectedGameList = ""

var body: some View 
    
    VStack        
    
        List(gameListViewModel.gameList)gameList in
        HStack 
            Text(gameList.gameName)
            
        
        .onAppear() self.gameListViewModel.fetchData()
    
        Picker(selection: $selectedGameList, label: Text(""))
        ForEach(gameListViewModel.gameList)  gameList in
            Text(gameList.gameName)
            
        
        .onAppear() self.gameListViewModel.fetchData()
     

这是 GameListViewModel

import Foundation
import Firebase

class GameListViewModel: ObservableObject

@Published var gameList = [GameListModel]()
let db = Firestore.firestore()

func fetchData() 

    db.collection("GameData").addSnapshotListener (querySnapshot, error) in
    guard let documents = querySnapshot?.documents else 
      print("No documents")
      return
    

    self.gameList = documents.map  queryDocumentSnapshot -> GameListModel in
      let data = queryDocumentSnapshot.data()
      let gameName = data["GameName"] as? String ?? ""
      return GameListModel(id: gameName, gameName: gameName)
      
    
  

这是游戏列表模型

import Foundation

struct GameListModel: Codable, Hashable,Identifiable 

var id: String
//var id: String = UUID().uuidString
var gameName: String

提前感谢您的帮助

【参考方案1】：

Picker不是动态设计的，所以数据更新时不会刷新，数据变化时尝试强制重建picker，如下图

    Picker(selection: $selectedGameList, label: Text(""))
    ForEach(gameListViewModel.gameList)  gameList in
        Text(gameList.gameName)
        
    .id(gameListViewModel.gameList)       // << here !!