菲利姆回应"cannot find 'cards' in scope"

Question

我按照本教程从firestore获取数据，并更改了我需要对应于我的模型的内容，但它一直响应"无法在范围中找到'cards'";我不知道我做错了什么。(我想我得到了MVVM标签正确)

<<p>视图/strong>

import SwiftUI
struct TestingView: View {
@ObservedObject private var viewModel = CardViewModel()
var body: some View {
List(viewModel.cards) {
Text(cards.name)
}
.onAppear() {
self.viewModel.fetchData()
}
}
} 

import Foundation
import Firebase
class CardViewModel: ObservableObject {
@Published var cards = [Cards]()
private var db = Firestore.firestore()
func fetchData() {
db.collection("cards").addSnapshotListener { (querySnapshot, error) in
guard let documents = querySnapshot?.documents else {
print("No documents")
return
}
self.cards = documents.map { queryDocumentSnapshot -> Cards in
let data = queryDocumentSnapshot.data()
let name = data["name"] as? String ?? ""
let pronoun = data["pronoun"] as? String ?? ""
let bio = data["bio"] as? String ?? ""
let profileURLString = data["profileURLString"] as? String ?? ""
let gradiantColor1 = data["gradiantColor1"] as? UInt ?? 0
let gradiantColor2 = data["gradiantColor2"] as? UInt ?? 0
let gradiantColor3 = data["gradiantColor3"] as? UInt ?? 0

return Cards(name: name, pronoun: pronoun, bio: bio, profileURLString:   profileURLString, gradiantColor1: gradiantColor1, gradiantColor2: gradiantColor2, gradiantColor3: gradiantColor3)
}
}
}
}

import Foundation
struct Cards: Identifiable {
var id = UUID().uuidString
var name: String
var pronoun: String
var bio: String
var profileURLString: String
var gradiantColor1: UInt
var gradiantColor2: UInt
var gradiantColor3: UInt
var profileURL: URL {
return URL(string: profileURLString)!
}
}

Answer 1

List将为其末尾闭包提供一个元素——参见我代码中的card in。然后，您可以访问Text元素中的特定card。

var body: some View {
List(viewModel.cards) { card in //<-- Here
Text(card.name) //<-- Here
}
.onAppear() {
self.viewModel.fetchData()
}
}
} 

我建议您可能要将struct Cards重命名为struct Card，因为它是一个卡。那么，您的数组将是@Published var cards = [Card]()——即Card的数组。从命名的角度来看，这将更有意义。