SwiftUI: How to make TextField become first responder?

Question

Here's my SwiftUI code:

struct ContentView : View {

    @State var showingTextField = false
    @State var text = ""

    var body: some View {
        return VStack {
            if showingTextField {
                TextField($text)
            }
            Button(action: { self.showingTextField.toggle() }) {
                Text ("Show")
            }
        }
    }
}

What I want is when the text field becomes visible, to make the text field become the first responder (i.e. receive focus & have the keyboard pop up).

Answer 1

It doesn't seem to be possible at the moment, but you can implement something similar yourself.

You can create a custom text field and add a value to make it become first responder.

struct CustomTextField: UIViewRepresentable {

    class Coordinator: NSObject, UITextFieldDelegate {

        @Binding var text: String
        var didBecomeFirstResponder = false

        init(text: Binding<String>) {
            _text = text
        }

        func textFieldDidChangeSelection(_ textField: UITextField) {
            text = textField.text ?? ""
        }

    }

    @Binding var text: String
    var isFirstResponder: Bool = false

    func makeUIView(context: UIViewRepresentableContext<CustomTextField>) -> UITextField {
        let textField = UITextField(frame: .zero)
        textField.delegate = context.coordinator
        return textField
    }

    func makeCoordinator() -> CustomTextField.Coordinator {
        return Coordinator(text: $text)
    }

    func updateUIView(_ uiView: UITextField, context: UIViewRepresentableContext<CustomTextField>) {
        uiView.text = text
        if isFirstResponder && !context.coordinator.didBecomeFirstResponder  {
            uiView.becomeFirstResponder()
            context.coordinator.didBecomeFirstResponder = true
        }
    }
}

Note: didBecomeFirstResponder is needed to make sure the text field becomes first responder only once, not on every refresh by SwiftUI!

You would use it like this...

struct ContentView : View {

    @State var text: String = ""

    var body: some View {
        CustomTextField(text: $text, isFirstResponder: true)
            .frame(width: 300, height: 50)
            .background(Color.red)
    }

}

P.S. I added a frame as it doesn't behave like the stock TextField, meaning there's more stuff going on behind the scenes.

More on Coordinators in this excellent WWDC 19 talk: Integrating SwiftUI

Tested on Xcode 11.4