如何检测 swiftui 中是否存在键盘

Question

I want to know if the keyboard is present when the button is pressed. How would I do this? I have tried but I don't have any luck. Thanks.

Answer 1

Using this protocol, KeyboardReadable , you can conform to any View and get keyboard updates from it.

KeyboardReadable protocol:

import Combine
import UIKit


/// Publisher to read keyboard changes.
protocol KeyboardReadable {
    var keyboardPublisher: AnyPublisher<Bool, Never> { get }
}

extension KeyboardReadable {
    var keyboardPublisher: AnyPublisher<Bool, Never> {
        Publishers.Merge(
            NotificationCenter.default
                .publisher(for: UIResponder.keyboardWillShowNotification)
                .map { _ in true },
            
            NotificationCenter.default
                .publisher(for: UIResponder.keyboardWillHideNotification)
                .map { _ in false }
        )
        .eraseToAnyPublisher()
    }
}

It works by using Combine and creating a publisher so we can receive the keyboard notifications.

With an example view of how it can be applied:

struct ContentView: View, KeyboardReadable {
    
    @State private var text: String = ""
    @State private var isKeyboardVisible = false
    
    var body: some View {
        TextField("Text", text: $text)
            .onReceive(keyboardPublisher) { newIsKeyboardVisible in
                print("Is keyboard visible? ", newIsKeyboardVisible)
                isKeyboardVisible = newIsKeyboardVisible
            }
    }
}

You can now read from the isKeyboardVisible variable to know if the keyboard is visible.

When the TextField is active with the keyboard showing, the following prints:

Is keyboard visible? true

When the keyboard is then hidden upon hitting return, the following prints instead:

Is keyboard visible? false

You can use keyboardWillShowNotification / keyboardWillHideNotification to update as soon as they keyboard starts to appear or disappear, and the keyboardDidShowNotification / keyboardDidHideNotification variants to update after the keyboard has appeared or disappeared. I prefer the will variant because the updates are instant for when the keyboard shows.

Answer 2

iOS 15:

You can use the focused(_:) view modifier and @FocusState property wrapper to know whether a text field is editing, and also change the editing state.

@State private var text: String = ""
@FocusState private var isTextFieldFocused: Bool

var body: some View {
    VStack {
        TextField("hello", text: $text)
            .focused($isTextFieldFocused)
        
        if isTextFieldFocused {
            Button("Keyboard is up!") {
                isTextFieldFocused = false
            }
        }
    }
}

Answer 3

My little improvement @George's answer.

Implement publisher right inside the View protocol

extension View {
  var keyboardPublisher: AnyPublisher<Bool, Never> {
    Publishers
      .Merge(
        NotificationCenter
          .default
          .publisher(for: UIResponder.keyboardWillShowNotification)
          .map { _ in true },
        NotificationCenter
          .default
          .publisher(for: UIResponder.keyboardWillHideNotification)
          .map { _ in false })
      .debounce(for: .seconds(0.1), scheduler: RunLoop.main)
      .eraseToAnyPublisher()
  }
}

I also added debounce operator in order to prevent true - false toggle when you have multiple TextFields and user moves between them.

Use in any View

struct SwiftUIView: View {
  @State var isKeyboardPresented = false
  @State var firstTextField = ""
  @State var secondTextField = ""
  
  var body: some View {
    VStack {
      TextField("First textField", text: $firstTextField)
      TextField("Second textField", text: $secondTextField)
    }
    .onReceive(keyboardPublisher) { value in
      isKeyboardPresented = value
    }
  }
}