SwiftUI非数组场景下如何传递upcomingmeeting至MeetingProfileView

原场景通过数组列表传递Meeting类型数据到MeetingProfileView，现新主视图不再依赖数组，需将MeetingViewModel中的可选属性upcomingmeeting作为参数传递给MeetingProfileView，以下是相关代码及最终解决方案：

ViewModel 代码 #

class MeetingViewModel: ObservableObject{
    init(){
        Task{ try await fetchAllMeetings() }
        Task{ try await fetchMeeting()}
    }
    
    @Published var upcomingmeeting: Meeting?
    @Published var meetings1 = [Meeting]() {
        didSet {
            if let first = meetings1.first {
                upcomingmeeting = first
            }
        }
    }
}

旧主视图代码（基于数组实现） #

import SwiftUI
import PhotosUI
struct MeetingSubView: View {
    @StateObject var viewModel = MeetingViewModel()

    var meet: Meeting
    var body: some View {
        NavigationStack{
            ForEach(viewModel.meetings1) { meet in
                ZStack {
                    NavigationLink(value: meet) {
                        EmptyView()
                    }.opacity(0.0)
                    
                    MeetingsRowViewDetailed(meeting: meet, viewModel: viewModel)
                        .onAppear {
                            if meet == viewModel.meetings1.last {
                                print("DEBUG: Paginate here..")
                            }
                        }
                }
            }
            .navigationDestination(for: Meeting.self, destination: { meet in
                MeetingProfileView( meet: meet)
            })
        }.onAppear(perform: {
            Task { try await viewModel.fetchMeeting()}
        })
    }
}

新主视图代码（需改造版本） #

@StateObject var viewModel = MeetingViewModel()

var body: some View{

       VStack{
             Text(viewModel.upcomingmeeting?.title ?? "no name")
             Text(viewModel.upcomingmeeting?.hostsite ?? "no name")
       }
       .foregroundColor(.white)
       .padding()
}

MeetingProfileView 代码 #

struct MeetingProfileView: View  {
    @StateObject var viewModel = MeetingViewModel()

    let meet:Meeting

    var body: some View {

        ZStack {
            ZStack{
                KFImage(URL(string: meet.profileImageUrl ?? ""))
                    .resizable()
                    .scaledToFill()
                    .frame(width: 800, height: 800)
//                    .clipShape(Rectangle())
                    .opacity(0.5)
                    .grayscale(0.8)
            }
        
            VStack(alignment: .center){
                VStack{
                    Text(meet.title)
                        .font(.title2)
                        .fontWeight(.semibold)
                    Text(meet.hostsite)
                    Text(meet.notes)
                        .padding(.horizontal, 100)
                        .padding()
                        .lineLimit(5)
                }
                .padding(.init(top: 50, leading: 100, bottom: 75, trailing: 100))
            }
            Spacer()
        }
        .onAppear {
            viewModel.fetchTechMeet(meet)
        }
    }
}

最终解决方案代码 #

由于upcomingmeeting是可选类型，需先安全解包再传递。通过if let解包后，使用NavigationLink直接将实例传入MeetingProfileView：

if let meet = viewModel.upcomingmeeting{
    VStack{
        NavigationLink(destination: MeetingProfileView(meet: meet)) {
            InputView3(title: viewModel.upcomingmeeting?.title ?? "", time: viewModel.upcomingmeeting?.hostsite ?? "", room: viewModel.upcomingmeeting?.citystate ?? "")
        }
    }
}

内容的提问来源于stack exchange，提问作者johnny