UIKit responder chain, gestures, menus, and input

UIKit routes events through controls, gesture recognizers, delegates, and the responder chain. Good interaction design makes ownership and precedence visible.

Follow the responder path

An unhandled action moves from the first responder through its superview, view controller, window, and application. This enables focused commands without global controller lookups.

override var keyCommands: [UIKeyCommand]? {
    [UIKeyCommand(input: "n", modifierFlags: .command,
                  action: #selector(createNote), discoverabilityTitle: "New Note")]
}

The command calls the same create-note path as the visible button. Enabled state follows the current scene and selection.

Define gesture relationships

let longPress = UILongPressGestureRecognizer(target: self, action: #selector(showMenu))
row.addGestureRecognizer(longPress)

Before adding recognizers, check whether buttons, context menus, swipe actions, and drag delegates already express the interaction. If recognizers compete, define failure requirements or simultaneous recognition intentionally.

Menus expose discoverable actions

button.menu = UIMenu(children: [
    UIAction(title: "Favorite", image: UIImage(systemName: "star")) { [weak self] _ in
        self?.favoriteSelectedNote()
    }
])
button.showsMenuAsPrimaryAction = true

Context menus and swipe actions supplement visible controls. Essential actions still need keyboard and accessibility routes.

Drag data, not view objects

Drag sessions transfer a typed representation or stable ID. Drop code validates the type and current domain object before mutation. Reordering also needs buttons or accessibility custom actions.

Validation boundary

Event routing, recognizer precedence, menus, keyboard commands, pointer input, drag sessions, and assistive alternatives remain Not verified without UIKit runtime testing.

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Series index: Zero to iOS Hero

References

Using responders and the responder chain to handle events explains event routing.
UIGestureRecognizer defines gesture recognition.
Menus and shortcuts covers commands and menus.