# Responding to control-based events using target-action Handle user input by connecting buttons, sliders, and other controls to your app’s code using the target-action design pattern. ## Discussion User interactions generate thousands of events for your app. Every swipe of the finger or button click, for instance, results in numerous events your app has to process. `Target-action` is a design pattern to help you handle these user interactions efficiently. By only registering actions against specific events on your controls, you simplify your event processing, while making your code more maintainable and easier to read. Use `target-action` to connect events directly from controls in your UI to methods in your code. ### Designate an object to handle control-related events When a person interacts with your control, the control needs to know where to send the event. The destination for the event is the *target*. View controllers make good targets because they’re adept at handling user interactions, as well as hosting UI controls.  ### Define the action methods you use to respond to events With a control assigned to the target, provide a function to call on that target when the event occurs. This is the *action* method. Action methods have a distinct signature: ```swift // UIKit. @IBAction func doSomething() @IBAction func doSomething(sender: Any) @IBAction func doSomething(sender: Any, forEvent event: UIEvent) // AppKit. @IBAction func doSomething() @IBAction func doSomething(sender: Any) ``` Xcode uses the `@IBAction` keyword to connect controls in Interface Builder to functions in your code. The keyword also bridges the Swift and Objective-C runtimes, enabling Swift code to call into Objective-C, which is where the target-action functionality lives. The `sender` parameter defines where the event comes from; for example, a button. Use the generic type `Any` to allow any control to call the action method, or specify the `sender` type when you need more information about the control for event processing. For example, set the `sender` type to [`UISlider`](/documentation/UIKit/UISlider) to read the slider thumb value when someone moves the slider left or right. ```swift // UIKit. @IBAction func adjustVolume(sender: UISlider) { print(sender.value) } // AppKit. @IBAction func adjustVolume(sender: NSSlider) { NSLog("%@", sender.stringValue) } ``` UIKit also supports coupling action methods to specific event types (see [`UIControl.Event`](/documentation/UIKit/UIControl/Event)). For example, to set up target-action for a user dragging their finger inside the bounds of a control, register for the event type [`touchDragInside`](/documentation/UIKit/UIControl/Event/touchDragInside). ### Connect controls to the action methods in Interface Builder With the `target` and `action` methods defined, you’re ready to connect them visually to the controls in Interface Builder. 1. Select the control (the `target`) you want to connect to the code (the `action`). 2. Control-drag the control to the view controller in the document outline. 3. Select the action method that the control connects to.   You can verify that the control and action are connected by moving the pointer over the circular dot to the left of the action method. When you do, Xcode highlights the control.  Another way to connect is to Control-drag the control from Interface Builder into the view controller.  Enter the name of the `action` method you’d like the control to call and then click Connect.  The following table lists the parameters available for configuration. |Parameter |Description | |----------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| |Connection|The type of connection to make. Select Action to establish a target-action relationship between the control and the target. | |Object |The `target` or object your control is connecting to. | |Name |The name of the function, or `action`, your control calls when the event occurs. | |Type |The type of the control sending the event. Choose `Any` if you don’t require any further information regarding the control’s state. Specify the control type if you require more information from the control for event processing. | |Event |The ``doc://com.apple.uikit/documentation/UIKit/UIEvent`` associated with the action. This feature is only available in UIKit. | |Arguments |The arguments to include in the signature of your target-action method. Choose None to include no arguments. Choose Sender to pass in the control type as the sender. Choose Sender and Event to pass in both the control type and the event that caused the action. This feature is available only in UIKit.| Connecting the target-action this way ensures the method signature and parameters are correct as Xcode generates the action method for you.  ### Connect a control to your code programmatically In UIKit, use the [`addTarget(_:action:for:)`](/documentation/UIKit/UIControl/addTarget(_:action:for:)) method to set up target-action programmatically on a control: ```swift import UIKit class ViewController: UIViewController { let signInButton = UIButton(type: .system) override func viewDidLoad() { super.viewDidLoad() signInButton.translatesAutoresizingMaskIntoConstraints = false signInButton.setTitle("Sign in", for: .normal) // Target-action. signInButton.addTarget(self, action: #selector(buttonTapped), for: .touchUpInside) view.addSubview(signInButton) signInButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true signInButton.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true } @IBAction func buttonTapped(sender: UIButton) { print("Sign in successful 🎉") } } ``` In AppKit, use the control’s `target` and `action` properties to set target-action programmatically: ```swift import Cocoa class ViewController: NSViewController { let signInButton = NSButton() override func viewDidLoad() { super.viewDidLoad() signInButton.translatesAutoresizingMaskIntoConstraints = false signInButton.title = "Sign in" // Target-action. signInButton.target = self signInButton.action = #selector(buttonTapped(sender:)) view.addSubview(signInButton) signInButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true signInButton.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true } @IBAction func buttonTapped(sender: NSButton) { print("Sign in successful 🎉") } } ``` ### Enable other objects to respond to control-related events When the object hosting the control isn’t the one you want handling the event, invoke the responder chain by passing in `nil` as the target. This causes the control to search the responder chain for the specified action method and invoke it when found. For more information, see [Using responders and the responder chain to handle events](/documentation/UIKit/using-responders-and-the-responder-chain-to-handle-events). --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)