SOLVED: NavigationSplitView Issue

@TazmanCoder

Jan '23

Happy New Year everyone,

I am trying to convert one of my apps from NavigationStack to NavigationSplitView. I am having some trouble and I am sure I'm missing something, just not sure what. The below code is what I am using. The Progam is a core data entity, lets say for testing purposes, its like this:

struct Program: : Identifiable, Hashable {
    var id = UUID()
    var name: String
    var date: String
}

When I use the following show the split view, I am able to select the first program and the detail will show up in the detail section, however, when I select a different program the detail isn't changing. As you can see I put some print statements in and can see those get printed out when I select a different program, yet the detail isn't changing.

I am not sure what I'm missing, any help would be appreciated.

struct ListOfProgramsView: View {
    // MARK: - Environment
    @EnvironmentObject var dataManager: DataManager

    // MARK: - State
    @State private var selectedProgram: Program.ID?
    @State private var currentSelectedProgram: Program?

    var body: some View {
        NavigationSplitView {
            List(dataManager.programs, selection: $selectedProgram) { program in
                ProgramsRowView(program: program)
                    .tag(program)
            }
            .navigationTitle(.nbProgramsViewTitle)
            .onChange(of: selectedProgram) { newProgramSelection in
                if let selection = newProgramSelection, let program = dataManager.programs.first(where: { $0.id == selection }) {
                    currentSelectedProgram = program
                    print("Changed Again: \(program.date.dateText(style: .medium))")
                }
            }
        } detail: {
            if let program = currentSelectedProgram {
                ModifyExistingProgramView(program: program, dataManager: dataManager)
                let _ = print("Program Date: \(program.date.dateText(style: .medium))")
            } else {
                NoProgramsView()
            }
        }
        .navigationSplitViewStyle(.balanced)
    }
}

Thanks, Taz

1

@TazmanCoder

Jan '23

Watched it, I already sent him a Ko-Fi....... The video was helpful and thats how I got as far as I have. However, I think I missing something and I just dont see it right now. So If you have any suggestions on how to change the code I would love to hear them.

Thanks

1

@Obelix

Jan '23

I didn't make too many changes. Mostly to add fake CoreData. When I select a Program from the list of Programs, the detail side updates.

// Run in Playgrounds to test assumptions, theories.
import SwiftUI
import PlaygroundSupport

struct Program: Identifiable, Hashable {
    var id =     UUID()
    var name:    String
    var date:    String
    var teacher: String

    static var examples = [
        Program(name: "Spells & Charms",  date: "1/1/2012 CE",      teacher: "Flitwick" ),
        Program(name: "Potions",          date: "2/29/1090",        teacher: "Slughorn" ),
        Program(name: "Divination",       date: "9/32/1066",        teacher: "Trelawney"),
        Program(name: "Sorcery",          date: "1/1/1666",         teacher: "Snape"    ),
        Program(name: "Arithmancy",       date: "Solstice 122 BCE", teacher: "Vector"   ),
        Program(name: "Famous Wizards",   date: "1/1/1000",         teacher: "Babbling" )
    ]
}

struct ListOfProgramsView: View {
    let allPrograms = Program.examples
    @State private var selectedProgram:        Program.ID?
    @State private var currentSelectedProgram: Program?

    var body: some View {
        NavigationSplitView {
            List(allPrograms, selection: $selectedProgram) { aProgram in
                Text("\(aProgram.name)").font(.title3)
            }
            .navigationTitle("Divine Programs")
            .onChange(of: selectedProgram) { newProgramSelection in
                if let selection = newProgramSelection, let program = allPrograms.first(where: { $0.id == selection }) {
                    currentSelectedProgram = program
                    print("You selected: \(program.name)")
                }
            }
        } detail: {
            if let program = currentSelectedProgram {
                ProgramsDetailView(program: program)
            } else {
                Text("select a program").font(.largeTitle).foregroundColor(.red)
            }
        }
        .navigationSplitViewStyle(.balanced)
    }
}

struct ProgramsDetailView: View {
    var program: Program
    var body: some View {
        VStack (spacing: 12) {
            Text("\(program.name)").font(.title)
            Text("by \(program.teacher)").font(.body)
            Text("First program: \(program.date)").font(.caption2)
        }
    }
}

PlaygroundPage.current.setLiveView(ListOfProgramsView() )  // <- This allows you to experiment with views in Playgrounds

1

@TazmanCoder

Jan '23

Ok,

Well, then I'm at a loss. From what I can see mine should be updating the detail, but its not. I'll have to look into it further. I was just not sure if the code I had was/should be working. From what you're telling me it is.

Thanks for your help @Obelix. I appreciate the time you took to look into it.

Taz

1

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