How can I use the return from my function as an argument for another function in onAppear-CodePudding

I am trying to use the result of the following function:

class GetRefresh: ObservableObject {
   let user = Auth.auth()
   var ref = Database.database().reference()
   @Published var refreshToken = ""
   func getRefresh() {
       ref.child("\(user.currentUser!.uid)").child("refreshUrl").getData { error, snapshot in
        guard error == nil else {
            print(error!.localizedDescription)
            return
        }
        let refreshUrl = snapshot.value as? String ?? "Unknown"
        let url = URL(string: refreshUrl.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!)
        var request = URLRequest(url: url!)
        request.httpMethod = "POST"
        URLSession.shared.dataTask(with:request) { (data, response, error) in
          if error != nil {
            print(error)
          } else {
            do {
              let parsedData = try JSONSerialization.jsonObject(with: data!) as! [String:Any]
              let token = parsedData["access_token"] as? String
              self.refreshToken = token!
            } catch let error as NSError {
              print(error)
            }
          }
        }.resume()
    }
  }
}

To pass as an argument to a Async service that is called in the onAppear of my view:

struct DevicesTab: View {
   @StateObject var callDevices = CallDevices()
   @StateObject var getRfrsh = GetRefresh()
   var ref: DatabaseReference!
   var body: some View {
       VStack(spacing: 0) {
           greeting.edgesIgnoringSafeArea(.top)
           messages
           Spacer()
       }
      .onAppear {
          getRfrsh.getRefresh()
          callDevices.getDevices(refreshToken: getRfrsh.refreshToken) //this fails
          }
      }
   }

The callDevices.getDevices is using the argument as a Header for its URLRequest.

If i hardcode the token in onAppear like:

.onAppear {
   getRfrsh.getRefresh()
   callDevices.getDevices(refreshToken: "HardcodedToken") //this works
  }

It works fine, albeit with a bit of a delay before the data is loaded but it works... I am sure the function is returning correctly as I was able to print it in GetRefresh.

CodePudding user response：

Well the reason for your code failing is you are not waiting for the network call to be completted before you call the next method.

Solution:

You could rework the code to be async. Or you could observe the changes of your @Publishedvar and call getDevices.

.onChange(of: getRfrsh.refreshToken) { newValue in
            callDevices.getDevices(refreshToken: newValue)
        }
.onAppear {
// to avoid repeatitive refreshing
      if getRfrsh.refreshToken == ""{
         getRfrsh.getRefresh()}
      }

But be aware. This will call getDevicesevery time the value changes.