如何将观察到的属性传递给其他类？ [英] How to pass observed properties to other classes?

问题描述

我创建了UserData的实例，以便其他类可以观察该实例并使用用户名显示必要的信息。我要在这里做的是，当用户登录时，将根据应用程序中的用户活动不时更新（即通过调用api）具有与用户相关的存储属性的不同类。
但是，它在属性初始化程序中显示错误无法使用实例成员 userData；属性初始化程序会在自身可用之前运行。任何想法如何解决这个问题？
我不确定如何将数据从单个ObservedObject传递到另一个。

I created an instance of UserData so that other classes can observe this instance and show the necessary information by using the username. What I am trying to do here is, when a user is logged in, different classes with user related stored properties will be updated ( i.e. by calling the api) from time to time according to the user activity in the app. However, it shows the error 'Cannot use instance member 'userData' within property initializer; property initializers run before 'self' is available'. Any ideas how to solve this? I am not sure how to pass the data from a single ObservedObject to another.

struct passingData: View {
    
    @ObservedObject var userData = UserData()
    @ObservedObject var images = ImageURL(userData: userData)
    @ObservedObject var payment = Payment(userData: userData)
    
    
    var body: some View {
        
        VStack{
            TextField("Enter userName", text: $userData.userName)
            Text("url is \(images.imageURL)")
            Text("Payment detail: \(payment.paymentDate)")
        }
    }
}


class Payment: ObservableObject{
    @Published var paymentDate = ""
    @ObservedObject  var userData: UserData
    init(userData: UserData){
        self.userData = userData
        loadPaymentDate()
    }
    
    func loadPaymentDate(){
        self.paymentDate = "last payment date from \(userData.userName) is someDate "
    }

}


class ImageURL: ObservableObject{
    @Published var imageURL = ""
    @ObservedObject  var userData: UserData
    init(userData: UserData){
        self.userData = userData
        loadImageURL()
    }
    
    func loadImageURL(){
        self.imageURL = "123_\(userData.userName).com"
    }
}



class UserData: ObservableObject{
    @Published var userName = ""
    
}

推荐答案

可能的解决方案：

struct passingData: View {
    
    @ObservedObject var userData: UserData
    @ObservedObject var images: ImageURL
    @ObservedObject var payment: Payment

    init() {
       let data = UserData()
      
       self.userData = data
       self.images = ImageURL(userData: data)
       self.payment = Payment(userData: data)
    }
    // ... other code

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