SwiftUI emoji picker using UIKit on iOS

EmojiPicker.swift

import SwiftUI

struct EmojiPickerView: UIViewRepresentable {
  @Binding var isFirstResponder: Bool
  var onPick: (String) -> Void
  var onDelete: () -> Void

  func makeUIView(context: Context) -> UIViewType {
    UIViewType(view: self)
  }

  func updateUIView(_ uiView: UIViewType, context: Context) {
    DispatchQueue.main.async {
      uiView.view = self
    }
  }

  class UIViewType: UIView, UIKeyInput {
    init(view: EmojiPickerView) {
      self.view = view
      super.init(frame: .zero)
    }

    required init?(coder: NSCoder) { nil }

    var view: EmojiPickerView {
      didSet {
        if view.isFirstResponder && !isFirstResponder {
          _ = becomeFirstResponder()
        }
        if !view.isFirstResponder && isFirstResponder {
          _ = resignFirstResponder()
        }
      }
    }

    var hasText: Bool = true
    override var canBecomeFirstResponder: Bool { true }
    override var canResignFirstResponder: Bool { true }
    override var textInputContextIdentifier: String? { "" }
    override var textInputMode: UITextInputMode? { .emoji }

    override func becomeFirstResponder() -> Bool {
      let result = super.becomeFirstResponder()
      if result && !view.isFirstResponder {
        view.isFirstResponder = true
      }
      return result
    }

    override func resignFirstResponder() -> Bool {
      let result = super.resignFirstResponder()
      if result && view.isFirstResponder {
        view.isFirstResponder = false
      }
      return result
    }

    func insertText(_ text: String) {
      if text.containsOnlyEmoji {
        view.onPick(text)
      } else {
        _ = resignFirstResponder()
      }
    }

    func deleteBackward() {
      view.onDelete()
    }
  }
}

extension UITextInputMode {
  static var emoji: UITextInputMode? {
    .activeInputModes.first { $0.primaryLanguage == "emoji" }
  }
}

extension Character {
  var isSimpleEmoji: Bool {
    guard let firstScalar = unicodeScalars.first else { return false }
    return firstScalar.properties.isEmoji && firstScalar.value > 0x238C
  }

  var isCombinedIntoEmoji: Bool {
    unicodeScalars.count > 1 && unicodeScalars.first?.properties.isEmoji ?? false
  }

  var isEmoji: Bool {
    isSimpleEmoji || isCombinedIntoEmoji
  }
}

extension String {
  var containsOnlyEmoji: Bool {
    !isEmpty && allSatisfy(\.isEmoji)
  }
}

struct EmojiPickerViewModifier: ViewModifier {
  @Binding var isPresented: Bool
  var onPick: (String) -> Void
  var onDelete: () -> Void

  func body(content: Content) -> some View {
    let _ = isPresented
    content.background {
      EmojiPickerView(
        isFirstResponder: $isPresented,
        onPick: onPick,
        onDelete: onDelete
      )
    }
  }
}

extension View {
  public func emojiPicker(
    isPresented: Binding<Bool>,
    onPick: @escaping (String) -> Void,
    onDelete: @escaping () -> Void = {}
  ) -> some View {
    modifier(EmojiPickerViewModifier(
      isPresented: isPresented,
      onPick: onPick,
      onDelete: onDelete
    ))
  }
}

EmojiPickerExample.swift

import SwiftUI

public struct EmojiPickerExample: View {
  public init() {}

  @State var emoji: String?
  @State var isPresentingPicker = false

  public var body: some View {
    VStack {
      Text(emoji ?? "no emoji")
        .font(.largeTitle)

      HStack {
        if isPresentingPicker {
          Button("Hide Picker") { isPresentingPicker = false }
        } else {
          Button("Open Picker") { isPresentingPicker = true }
        }

        Button("Clear") { emoji = nil }
      }
      .buttonStyle(.borderedProminent)
      .controlSize(.large)
    }
    .emojiPicker(
      isPresented: $isPresentingPicker,
      onPick: { emoji = $0 },
      onDelete: { emoji = nil }
    )
  }
}

EmojiPickerExample.mp4