displaying alert on picker select SwiftUI-CodePudding

i want to display an alert box when a user selects something in a form picker the user then have to confirm their choice before the value changes. right now my code looks like this(just from some tutorial):

            NavigationView {
            Form {
                Section {
                    Picker("Strength", selection: $selectedStrength) {
                        ForEach(strengths, id: \.self) {
                            Text($0)
                        
                            
                        }
                    }
                }
            }
        }

I have tried using onChange() but ideally the check should be before the value changes.

CodePudding user response：

If you want to ask the user to confirm before the selection changes you would need to implement a custom binding with a second var. With this you would be able to cancel the selection if necessary.

struct Test: View{
    @State private var selectedStrength: String = ""
    @State private var askForStrength: String = ""
    @State private var ask: Bool = false
    let strengths = ["1","2","3"]
    var body: some View{
        NavigationView {
            Form {
                Section {
                    Picker("Strength", selection: Binding(get: {selectedStrength}, set: {
                        //assign the selection to the temp var
                        askForStrength = $0
                        // show the Alert
                        ask = true
                    })) {
                        ForEach(strengths, id: \.self) {
                            Text($0)
                        }
                    }
                }
            }
        }.alert(isPresented: $ask) {
            // Here ask the user if selection is correct and apply the temp var to the selection
            Alert(title: Text("select?"), message: Text("Do you want to select \(askForStrength)"), primaryButton: .default(Text("select"), action: {selectedStrength = askForStrength}), secondaryButton: .cancel())
        }
    }
}

CodePudding user response：

You can do it this way; having an alert after the value is clicked and a temp variable for storing pre-selected data. Code is below the image:

import SwiftUI

struct ContentView: View {

let animals = ["dog", "cat", "pig"]
@State var selected = ""
@State var finalResult = ""
@State var alert = false

var body: some View {
    NavigationView {
        Form {
            Section {
                Picker("Animals", selection: $selected) {
                    ForEach(animals, id: \.self) {
                        Text($0)
                    }
                }
                .onChange(of: selected) { _ in
                    alert.toggle()
                }
                Text("You have confirmed to select this: \(finalResult)")
            }
            .alert("Confirm selection?", isPresented: $alert) {
                Button("Confirm", role: .destructive) {
                    finalResult = selected
                }
            }
        }
    }
  }
}