UIKit text, forms, keyboards, focus, and validation

UIKit form controls edit temporary input. The persisted note changes only after the draft passes validation and Save succeeds.

Keep a draft beside the controls

struct NoteDraft: Equatable {
    var title: String
    var body: String

    var titleError: String? {
        title.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
            ? "Enter a title."
            : nil
    }
}

Text-field and text-view delegates copy edits into this draft. Cancel compares it with the original. A save failure preserves it.

Configure input as a hint

titleField.placeholder = "Title"
titleField.returnKeyType = .next
titleField.textContentType = nil
titleField.adjustsFontForContentSizeCategory = true

Keyboard type, capitalization, and content type help entry. They do not validate pasted text, dictation, hardware keyboards, or automation.

Move focus intentionally

func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    bodyView.becomeFirstResponder()
    return true
}

Validation failure can focus the first invalid control and expose a nearby error. VoiceOver announcements and reading order require separate testing.

Follow the keyboard layout guide

Constrain the form or bottom action region against keyboardLayoutGuide when the deployment floor supports it. Do not translate the whole root view by notification height. Split keyboards, floating keyboards, rotation, hardware keyboards, and interactive dismissal break that assumption.

Validate one action path

Toolbar Save, keyboard shortcut, and Return submission call the same method. The method updates attempted-save state, renders errors, builds a domain command, prevents duplicate work, and preserves the draft on failure.

Validation boundary

Text entry, delegate order, focus, keyboard geometry, validation announcements, hardware input, and Dynamic Type remain Not verified.

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References

UITextField provides single-line text input.
UITextView provides multiline editing.
UIKeyboardLayoutGuide represents keyboard-obscured layout.