Playgrounds App on iPad not updating UI on @State change

Question

Created Feb ’21

Replies 5

Boosts 0

Views 1.8k

Participants 5

iPad Pro running iOS 14.4, Playgrounds App version 3.4

Super simple @State example doesn’t update the UI. Clicking the button increments the tapCount variable, but the UI doesn’t update to show the new value. Isn’t it supposed to?

Am I using an old code example or otherwise doing something wrong? This exact same code works fine on a Playground in Xcode.

Code Block Swiftimport SwiftUI
import PlaygroundSupport
struct ContentView: View {
    @State private var tapCount = 0
    var body: some View {
        Button("Tap count: \(tapCount)") {
            tapCount += 1
        }
    }
}
PlaygroundPage.current.setLiveView(ContentView())

Boost

Answer 1

DTS Engineer OP

Apple

Feb ’21

Well, that’s interesting. I put your code into Playgrounds on the Mac (1) and it worked. However, the same code fails as you described in Playgrounds on my iPad. Weird, and definitely bugworthy.

Please post your bug number, just for the record.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@apple.com"

(1) Not an Xcode playground, but the Mac Catalyst version of the iOS Playgrounds app.

0

Answer 2

wrees3 OP

Feb ’21

I think this is the bug number: FB9018696

0

Answer 3

PaulSolt OP

May ’21

I’m seeing the same issue on my iPad Pro 11”

FB9121354: Swift Playgrounds on iPad does not update UI for @State variables

The code works on Mac, not on iPad Playgrounds.

import SwiftUI
import PlaygroundSupport

struct ContentView: View {

    @State var isSelected: Bool = true
    @State var useRedText = false

    var body: some View {

        VStack {

            Text("SwiftUI on iPad")

                .font(.headline)

                .padding(20)

                .background(Color.red)

                .cornerRadius(10)

            Text("Paul Rocks!")

                .font(.largeTitle)

                .padding(20)

                .background(isSelected ? Color.orange : Color.blue) //color())

                .cornerRadius(30)

                .onTapGesture { 

                    print("Paul Rocks")

                    isSelected.toggle()

                }

            

            Button("Hello World") {

                    // flip the Boolean between true and false

                    self.useRedText.toggle()      

                }

                .foregroundColor(useRedText ? .red : .blue)

        }

    }

    

    func color() -> Color {

        isSelected ? Color.orange : Color.blue

    }

}


PlaygroundPage.current.setLiveView(ContentView())

0

Answer 4

LumuS OP

May ’21

Just tested both codes (wrees3 and PaulSolt) on my iPad Air (2020) iOS 14.6, Playground App 3.4.1 (1302.34)

Both code don't work by default. But if I turn off "Enable Results" they both work perfect with no changes in code.

6

Answer 5

AdskiYojeG OP

May ’21

LumuS many thanks! So simply. Everything is work. May be you know how to switch it off by default?

0