如何通过在 swiftui 中使用 ID 引用来覆盖可识别对象？

Question

我已经简化了我的代码，以便更容易看到我正在尝试做什么，我正在构建一个评级提要，这些评级来自我“关注”的任何人的 firebase 文档

我想做的就是每当 firebase 说我的评论有新更新时，更改可识别的，而不是必须重新加载我关注的每个人的每条评论。

这是我的观点：

import SwiftUI
import Firebase

struct Rating: Identifiable {
    var id: String
    var review: String
    var likes: Int
}

struct Home: View {
    
    @ObservedObject var feedViewModel = FeedViewModel()

    var body: some View {
        VStack{
                         
           ForEach(self.feedViewModel.allRatings, id: \.id){ rating in
               Text(rating.review)
               Text("\(rating.likes)")
           }
        }
     }
}

这是我的 FeedViewModel 函数：

class FeedViewModel: ObservableObject {

     @Published var following = ["qedXpEcaRLhIa6zWjfJC", "1nDyDT4bIa7LBEaYGjHG", "4c9ZSPTQm2zZqztNlVUp", "YlvnziMdW8VfibEyCUws"]
     @Published var allRatings = [Rating]()

     init() {
         for doc in following {
              
              // For each person (aka doc) I am following we need to load all of it's ratings and connect the listeners
              getRatings(doc: doc)
              initializeListener(doc: doc)

          }
      }


    func getRatings(doc: String) {
        
        db.collection("ratings").document(doc).collection("public").getDocuments() { (querySnapshot, err) in
            
            if let err = err {
                print("Error getting documents: \(err)")
            } else {
                
 
                // We have to use += because we are loading lots of different documents into the allRatings array, allRatings turns into our feed of reviews.
                self.allRatings += querySnapshot!.documents.map { queryDocumentSnapshot -> Rating in
                   let data = queryDocumentSnapshot.data()
                   let id = ("\(doc)-\(queryDocumentSnapshot.documentID)")
                   let review = data["review"] as? String ?? ""
                   let likes = data["likes"] as? Int ?? 0

                   return Rating(id: id, review: review, likes: likes)

                }
            }
      }


    func initializeListener(doc: String){
        
        db.collection("ratings").document(doc).collection("public")
            .addSnapshotListener { (querySnapshot, error) in
            
            guard let snapshot = querySnapshot else {
                print("Error listening for channel updates")
                return
            }

            snapshot.documentChanges.forEach { change in

                for document in snapshot.documents{

                   let data = document.data()
                   let id = ("\(doc)-\(document.documentID)")
                   let review = data["review"] as? String ?? ""
                   let likes = data["likes"] as? Int ?? 0

                   // I thought swiftui Identifiables would be smart enough to not add another identifiable if there is already an existing one with the same id, but I was wrong, this just duplicates the rating
                   // self.allRatings.append(Rating(id: id, review: review, likes: likes))

                   // This is my current solution, to overwrite the Rating in the allRatings array, however I can not figure out how to get the index of the changed rating
                   // "0" should be replaced with whatever Rating index is being changed
                   self.allRatings[0] = Rating(id: id, review: review, likes: likes)

                }
            }
        }
     }

}

我只想让每个评级的“喜欢”实时更新，只要有人喜欢评级。这看起来很简单，但我对 swiftui 还比较陌生，所以我可能完全不知道我是怎么做的。非常感谢任何帮助！

Answer 1

经过一周的努力，我终于明白了，希望这对某人有所帮助，如果你想覆盖数组中的可识别项，请使用你的 id 找到索引。在我的例子中，我的 ID 是 firebaseCollectionID + firebaseDocumentID，所以这使它始终 100% 唯一并且它允许我从快照侦听器引用它...

let index = self.allRatings.firstIndex { (Rating) -> Bool in
    Rating.id == id
}

然后覆盖它：

self.allRatings[index!] = Rating(id: id, review: review, likes: likes)

如何通过在 swiftui 中使用 ID 引用来覆盖可识别对象？

How do I overwrite an identifiable object by refrencing it with an ID in swiftui?

swift

firebase

google-cloud-firestore

swiftui

identifiable