FocusStateのサンプル

FocusState.swift

import SwiftUI

// MARK: - ContentView

struct ContentView: View {
    var body: some View {
        MyForm()
            .frame(maxHeight: .infinity, alignment: .top)
            .padding()
            .padding(.top)
    }
}

// MARK: - MyForm

struct MyForm: View {
    @State var profile = Profile()
    @FocusState var focus: KeyPath<Profile, String>?

    var body: some View {
        VStack(spacing: 20) {
            MyTextField("氏名", text: $profile.fullName, isRequired: true)
                .focused($focus, equals: \.fullName)
                .onSubmit { focus = \.phoneticName }

            MyTextField("フリガナ", text: $profile.phoneticName, isRequired: true)
                .focused($focus, equals: \.phoneticName)
                .onSubmit { focus = \.phoneNumber }

            MyTextField("電話番号", text: $profile.phoneNumber)
                .focused($focus, equals: \.phoneNumber)
                .onSubmit { focus = \.emailAddress }

            MyTextField("メールアドレス", text: $profile.emailAddress)
                .focused($focus, equals: \.emailAddress)
        }
        .onAppear {
            focus = \.fullName
        }
    }
}

// MARK: - MyTextField

struct MyTextField: View {
    var label: String
    var placeholder: String
    @Binding var text: String
    var isRequired: Bool = false

    var body: some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack(spacing: 2) {
                Text(label)
                if isRequired {
                    Image(systemName: "asterisk")
                        .imageScale(.small)
                        .foregroundStyle(.red)
                }
            }
            .font(.subheadline)
            .fontWeight(.semibold)

            TextField(placeholder, text: $text)
                .font(.body)
                .textFieldStyle(.roundedBorder)
        }
    }
}

extension MyTextField {
    init(_ label: String, placeholder: String? = nil, text: Binding<String>, isRequired: Bool = false) {
        self.init(
            label: label, placeholder: placeholder ?? label, text: text, isRequired: isRequired)
    }
}

// MARK: - Profile

struct Profile: Hashable, Identifiable {
    var id = UUID()
    var fullName: String = ""
    var phoneticName: String = ""
    var phoneNumber: String = ""
    var emailAddress: String = ""
}

// MARK: - Preview

#Preview {
    ContentView()
}