SwiftUI TextField Focus, onSubmit, and onChange
@FocusState moves the cursor programmatically, onSubmit chains fields through return, and onChange validates as users type — the wiring of real forms.
import SwiftUI
struct LoginForm: View {
enum Field { case email, password }
@FocusState private var focus: Field?
@State private var email = ""
@State private var password = ""
var body: some View {
Form {
TextField("Email", text: $email)
.focused($focus, equals: .email)
.submitLabel(.next)
SecureField("Password", text: $password)
.focused($focus, equals: .password)
.submitLabel(.go)
}
.onSubmit {
switch focus {
case .email: focus = .password
case .password: focus = nil // dismiss & sign in
default: break
}
}
.onChange(of: email) { _, newValue in
email = newValue.lowercased()
}
.onAppear { focus = .email }
}
}
Focus as state
@FocusState makes the keyboard's location a value you read and write:
@FocusState private var focus: Field?
TextField(…).focused($focus, equals: .email)Set focus = .password and the cursor moves; set nil and the keyboard drops. Auto-focusing the first field onAppear (after a brief delay on some presentations) removes one tap from every form visit. A Bool-flavored @FocusState exists for single fields.
Return-key choreography
onSubmit fires when the user hits return in any field inside it. Combined with submitLabel, forms gain the native flow users expect: Next advances, Go submits. Submit handlers attach per-field or once on the container — the container form with a switch keeps the flow in one readable place.
Live reaction with onChange
onChange(of: text) { old, new in … } is where typing becomes behavior: lowercase emails, strip spaces from codes, cap lengths, set validation flags. For expensive consequences (search requests), pair with .task(id: text) for free cancellation-based debouncing.
Growing fields
TextField("Notes", text: $notes, axis: .vertical) with lineLimit(3...6) wraps and grows — the modern alternative to TextEditor for short multi-line input inside forms.
Common mistakes
- Forgetting submitLabel, leaving 'return' on a field that actually submits.
- Heavy synchronous work in onChange on every keystroke.
- Focus mutations during view updates; defer to user actions or task blocks.
Related reference
TextField binds editable text with a placeholder label, keyboardType for input-appropriate keys, textContentType for autofill, and capitalization and autocorrection control.
SecureField masks input for secrets, pairs with textContentType for password managers and strong-password suggestions, and composes with TextField for reveal toggles.
searchable adds the platform search field, you own the filtering. Add searchSuggestions with searchCompletion, surface no-results states, and dismiss with the environment action.