passing parameter to a SwiftUI Sheet

Question

I need to pass a parameter calledFrom to a Sheet in SwiftUI.
Strangely, the parameter is not used on the first call, but it works on the following ones.

import SwiftUI

struct ContentView: View {
    @State var showSheet = false
    @State var calledFrom = -1
    
    var body: some View {
        ForEach((1...4), id: \.self) { i in
            getButton(i)
        }
        .sheet(isPresented: $showSheet) { Dialog(calledFrom: calledFrom) }
        .padding()
    }
    
    func getButton(_ i : Int) -> some View {
        return Button("\(i)"){print("Button \(i) pressed"); calledFrom = i; showSheet = true }
    }
}

struct Dialog: View {
  var calledFrom : Int
  @Environment(\.presentationMode) private var presentationMode
  var body: some View {
    VStack{
      Text("Called from Button \(calledFrom)")
        Button("close"){presentationMode.wrappedValue.dismiss()}
    }
    .padding()
  }
}

Common issue in iOS 14. You need to use sheet(item:) instead of sheet(isPresented:). See: stackoverflow.com/questions/66190082/… and stackoverflow.com/questions/66162219/… — jnpdx
– jnpdx, Commented Apr 3, 2021 at 22:39

jnpdx · Accepted Answer · 2021-04-03 22:44:22Z

20

You have to use sheet(item:) to get the behavior you're looking for. In iOS 14, the sheet view is calculated before the @State changes:


struct ActiveItem : Identifiable {
    var calledFrom: Int
    var id: Int { return calledFrom }
}

struct ContentView: View {
    @State var activeItem : ActiveItem?
    
    var body: some View {
        ForEach((1...4), id: \.self) { i in
            getButton(i)
        }
        .sheet(item: $activeItem) { item in
            Dialog(calledFrom: item.calledFrom)
        }
        .padding()
    }
    
    func getButton(_ i : Int) -> some View {
        return Button("\(i)"){
            print("Button \(i) pressed");
            activeItem = ActiveItem(calledFrom: i)
        }
    }
}

answered Apr 3, 2021 at 22:44

jnpdx

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4 Comments

Bartłomiej Semańczyk May 9 at 9:35

Is there a way to have ActiveItem nullable? Why? Because I need there either create new object or edit existing one. This is totally the same layout and the only difference is ActiveItem is nill or not.

jnpdx May 10 at 15:06

It’s already an optional in my answer

Bartłomiej Semańczyk May 10 at 18:17

it is nullable, but sheet(item will not be called if there is a nil value...🤷🏼‍♂️

jnpdx May 11 at 4:10

You could put the value you want inside another wrapper struct and make the inner value optional

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