Binding with optional struct

I get the error "Value of optional type 'Photo?' must be unwrapped to refer to member 'name' of wrapped base type 'Photo'" when I try to send a optional struct on a binding of a TextField.

The content view code example:

import SwiftUI

struct ContentView: View {
    @StateObject var viewModel = ContentViewViewModel()
    
    private var photos = [
        Photo(id: UUID(), name: "Exclamation", data: (UIImage(systemName: "exclamationmark.triangle")?.jpegData(compressionQuality: 1))!),
        Photo(id: UUID(), name: "Circle", data: (UIImage(systemName: "circle.fill")?.jpegData(compressionQuality: 1))!)
    ]
    
    var body: some View {
        VStack {
            DetailView(viewModel: viewModel)
        }
        .onAppear {
            viewModel.selectedPhoto = photos[0]
        }
    }
}

The view model code example:

import Foundation

@MainActor
final class ContentViewViewModel: ObservableObject {
    @Published var photos = [Photo]()
    @Published var selectedPhoto: Photo?
}

The detail view code example (that uses the content view's view model):

import SwiftUI

struct DetailView: View {
    @ObservedObject var viewModel: ContentViewViewModel
    
    var body: some View {
        TextField("Photo name here...", text: $viewModel.selectedPhoto.name)
    }
}

Note that for some reasons I need the selectedPhoto property be optional.

Solution

You can create your own custom @Binding, so you can handle the process between getting data and set the updated here is an example:

If what you want is to select the photo in a List or Foreach you can bind directly to the array.

import SwiftUI

 struct Photo {
     let id: UUID
     var name: String
     let data: Data
 }

 @MainActor
 final class ContentViewViewModel: ObservableObject {
     @Published var photos = [Photo]()
     @Published var selectedPhoto: Photo?
 }

 struct optionalBinding: View {

     @StateObject var viewModel = ContentViewViewModel()

     private var photos = [
         Photo(id: UUID(), name: "Exclamation", data: (UIImage(systemName: "exclamationmark.triangle")?.jpegData(compressionQuality: 1))!),
         Photo(id: UUID(), name: "Circle", data: (UIImage(systemName: "circle.fill")?.jpegData(compressionQuality: 1))!)
     ]

     var body: some View {
         VStack {
             DetailView2(viewModel: viewModel)

             Button("Select Photo") {
                 viewModel.selectedPhoto = photos[0]
             }
         }
     }
 }

 struct DetailView2: View {
     @ObservedObject var viewModel: ContentViewViewModel

     var body: some View {
         Text(viewModel.selectedPhoto?.name ?? "No photo selected")
         TextField("Photo name here...", text: optionalBinding())
     }

     func optionalBinding() -> Binding<String> {
         return Binding<String>(
             get: {
                 guard let photo = viewModel.selectedPhoto else {
                     return ""
                 }
                 return photo.name
             },
             set: {
                 guard let _ = viewModel.selectedPhoto else {
                     return
                 }
                 viewModel.selectedPhoto?.name = $0
                 //Todo: also update the array
             }
         )
     }
 }