swift - @ObservedObject 更改未在异步操作后反映

Question

我是 Swift 的初学者，我根据一些教程粗略地尝试创建一个 MVVM 有点架构但是我发现具有一些 @Published 值属性的@ObservedObject 变量 wallpaperViewModel 并不能反映网络操作后的变化网络操作工作正常，我通过将接收到的值打印到控制台来确认它

这是所需的代码

壁纸视图模型

class WallpaperViewModel: ObservableObject {
    @Published var wallpapers : [Wallpaper] = [Wallpaper]()
    @Published var allBanners : [Banner] = [Banner]()
    @Published var error: String = ""

    
    //Handles error in requests, enum NetworkError has three cases unknown custom requestFailed
    func errorHandler(error: NetworkError){
         switch error {
             case .custom(let customErr):
                 self.error = customErr
                 print(customErr)
             case .requestFailed:
                 self.error = "Request Failed,Please check your internet connection"
                 print("Request Failed")
             case .unknown:
                 self.error = "An unknown error occured"
                 print ("An unknown error occured")
             case .networkNotConnected:
                 self.error = "Network not connected"
                 print ("Network not connected")
         }
     }
    
    
    func getAllWallpapersfromApi (order: String, page: String){
            NetworkingUtil().getAllWallpapers(orderBy: order, page: page){result in
                switch result{
                case .success(let wallpapers):
                         self.wallpapers = wallpapers
                case .failure(let err):
                        self.errorHandler(error: err)
            }
        }
 
    }
    
    func getAllBanners(){
        NetworkingUtil().getAllBanners(){result in
            switch result{
            case .success(let banners):
                self.allBanners = banners
                print("allBanners: (in VM)", banners)
            case .failure(let error):
                self.errorHandler(error: error)
            }
        }
    }
}

这是我的主要观点

struct ContentView: View {
    
    @ObservedObject var wallpaperViewModel = WallpaperViewModel()
    @State private var selectedTab = 0
    var body: some View {
        
        VStack{
            if(wallpaperViewModel.error.isEmpty){
                TabView(selection: $selectedTab){
                    if(wallpaperViewModel.allBanners.count == 0){
                       Text("Loading..")
                   }
                   else{
                    ForEach(0..<wallpaperViewModel.allBanners.count){ bannerIndex in
                           //let banner = banners[bannerIndex]
                           Image("cover-cheetah")
                               .resizable()
                               .scaledToFill()
                               .frame(height:selectedTab == bannerIndex ? 230 : 180)
                               .cornerRadius(12)
                       }
                   }
                   
               }
               .frame(height: 230)
               .tabViewStyle(PageTabViewStyle())
               .animation(.easeOut)
               .padding(.horizontal)
            }
            else{
                Text("\(wallpaperViewModel.error)")
            }
        }
        .onAppear{
            self.wallpaperViewModel.getAllBanners()
            print("allBanners in ContentView",wallpaperViewModel.allBanners)
            self.wallpaperViewModel.getAllWallpapersfromApi(order: "created", page: String(0))
            print("allWallpapers in ContentView",wallpaperViewModel.wallpapers)
        }

这是记录到控制台的值

这是模拟器上的输出

标签： swiftswiftuiobservedobject