如何向 UIView 添加触摸事件？

Question

How do I add a touch event to a UIView?
I try:

UIView *headerView = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, nextY)] autorelease];
[headerView addTarget:self action:@selector(myEvent:) forControlEvents:UIControlEventTouchDown];
// ERROR MESSAGE: UIView may not respond to '-addTarget:action:forControlEvents:'

I don't want to create a subclass and overwrite

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

Answer 1

In iOS 3.2 and higher, you can use gesture recognizers. For example, this is how you would handle a tap event:

//The setup code (in viewDidLoad in your view controller)
UITapGestureRecognizer *singleFingerTap = 
  [[UITapGestureRecognizer alloc] initWithTarget:self 
                                          action:@selector(handleSingleTap:)];
[self.view addGestureRecognizer:singleFingerTap];

//The event handling method
- (void)handleSingleTap:(UITapGestureRecognizer *)recognizer
{
  CGPoint location = [recognizer locationInView:[recognizer.view superview]];

  //Do stuff here...
}

There are a bunch of built in gestures as well. Check out the docs for iOS event handling and UIGestureRecognizer . I also have a bunch of sample code up on github that might help.

Answer 2

Gesture Recognizers

There are a number of commonly used touch events (or gestures) that you can be notified of when you add a Gesture Recognizer to your view. They following gesture types are supported by default:

• UITapGestureRecognizer Tap (touching the screen briefly one or more times)
• UILongPressGestureRecognizer Long touch (touching the screen for a long time)
• UIPanGestureRecognizer Pan (moving your finger across the screen)
• UISwipeGestureRecognizer Swipe (moving finger quickly)
• UIPinchGestureRecognizer Pinch (moving two fingers together or apart - usually to zoom)
• UIRotationGestureRecognizer Rotate (moving two fingers in a circular direction)

In addition to these, you can also make your own custom gesture recognizer.

Adding a Gesture in the Interface Builder

Drag a gesture recognizer from the object library onto your view.

Control drag from the gesture in the Document Outline to your View Controller code in order to make an Outlet and an Action.

This should be set by default, but also make sure that User Action Enabled is set to true for your view.

Adding a Gesture Programmatically

To add a gesture programmatically, you (1) create a gesture recognizer, (2) add it to a view, and (3) make a method that is called when the gesture is recognized.

import UIKit
class ViewController: UIViewController {

    @IBOutlet weak var myView: UIView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 1. create a gesture recognizer (tap gesture)
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(sender:)))
        
        // 2. add the gesture recognizer to a view
        myView.addGestureRecognizer(tapGesture)
    }
    
    // 3. this method is called when a tap is recognized
    @objc func handleTap(sender: UITapGestureRecognizer) {
        print("tap")
    }
}

Notes

• The sender parameter is optional. If you don't need a reference to the gesture then you can leave it out. If you do so, though, remove the (sender:) after the action method name.
• The naming of the handleTap method was arbitrary. Name it whatever you want using action: #selector( someMethodName (sender:)) .

More Examples

You can study the gesture recognizers that I added to these views to see how they work.

Here is the code for that project:

import UIKit
class ViewController: UIViewController {
    
    @IBOutlet weak var tapView: UIView!
    @IBOutlet weak var doubleTapView: UIView!
    @IBOutlet weak var longPressView: UIView!
    @IBOutlet weak var panView: UIView!
    @IBOutlet weak var swipeView: UIView!
    @IBOutlet weak var pinchView: UIView!
    @IBOutlet weak var rotateView: UIView!
    @IBOutlet weak var label: UILabel!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Tap
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTap))
        tapView.addGestureRecognizer(tapGesture)
        
        // Double Tap
        let doubleTapGesture = UITapGestureRecognizer(target: self, action: #selector(handleDoubleTap))
        doubleTapGesture.numberOfTapsRequired = 2
        doubleTapView.addGestureRecognizer(doubleTapGesture)
        
        // Long Press
        let longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress(gesture:)))
        longPressView.addGestureRecognizer(longPressGesture)
        
        // Pan
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan(gesture:)))
        panView.addGestureRecognizer(panGesture)
        
        // Swipe (right and left)
        let swipeRightGesture = UISwipeGestureRecognizer(target: self, action: #selector(handleSwipe(gesture:)))
        let swipeLeftGesture = UISwipeGestureRecognizer(target: self, action: #selector(handleSwipe(gesture:)))
        swipeRightGesture.direction = UISwipeGestureRecognizerDirection.right
        swipeLeftGesture.direction = UISwipeGestureRecognizerDirection.left
        swipeView.addGestureRecognizer(swipeRightGesture)
        swipeView.addGestureRecognizer(swipeLeftGesture)
        
        // Pinch
        let pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(handlePinch(gesture:)))
        pinchView.addGestureRecognizer(pinchGesture)
        
        // Rotate
        let rotateGesture = UIRotationGestureRecognizer(target: self, action: #selector(handleRotate(gesture:)))
        rotateView.addGestureRecognizer(rotateGesture)
        
    }
    
    // Tap action
    @objc func handleTap() {
        label.text = "Tap recognized"
        
        // example task: change background color
        if tapView.backgroundColor == UIColor.blue {
            tapView.backgroundColor = UIColor.red
        } else {
            tapView.backgroundColor = UIColor.blue
        }
        
    }
    
    // Double tap action
    @objc func handleDoubleTap() {
        label.text = "Double tap recognized"
        
        // example task: change background color
        if doubleTapView.backgroundColor == UIColor.yellow {
            doubleTapView.backgroundColor = UIColor.green
        } else {
            doubleTapView.backgroundColor = UIColor.yellow
        }
    }
    
    // Long press action
    @objc func handleLongPress(gesture: UILongPressGestureRecognizer) {
        label.text = "Long press recognized"
        
        // example task: show an alert
        if gesture.state == UIGestureRecognizerState.began {
            let alert = UIAlertController(title: "Long Press", message: "Can I help you?", preferredStyle: UIAlertControllerStyle.alert)
            alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
            self.present(alert, animated: true, completion: nil)
        }
    }
    
    // Pan action
    @objc func handlePan(gesture: UIPanGestureRecognizer) {
        label.text = "Pan recognized"
        
        // example task: drag view
        let location = gesture.location(in: view) // root view
        panView.center = location
    }
    
    // Swipe action
    @objc func handleSwipe(gesture: UISwipeGestureRecognizer) {
        label.text = "Swipe recognized"
        
        // example task: animate view off screen
        let originalLocation = swipeView.center
        if gesture.direction == UISwipeGestureRecognizerDirection.right {
            UIView.animate(withDuration: 0.5, animations: {
                self.swipeView.center.x += self.view.bounds.width
            }, completion: { (value: Bool) in
                self.swipeView.center = originalLocation
            })
        } else if gesture.direction == UISwipeGestureRecognizerDirection.left {
            UIView.animate(withDuration: 0.5, animations: {
                self.swipeView.center.x -= self.view.bounds.width
            }, completion: { (value: Bool) in
                self.swipeView.center = originalLocation
            })
        }
    }
    
    // Pinch action
    @objc func handlePinch(gesture: UIPinchGestureRecognizer) {
        label.text = "Pinch recognized"
        
        if gesture.state == UIGestureRecognizerState.changed {
            let transform = CGAffineTransform(scaleX: gesture.scale, y: gesture.scale)
            pinchView.transform = transform
        }
    }
    
    // Rotate action
    @objc func handleRotate(gesture: UIRotationGestureRecognizer) {
        label.text = "Rotate recognized"
        
        if gesture.state == UIGestureRecognizerState.changed {
            let transform = CGAffineTransform(rotationAngle: gesture.rotation)
            rotateView.transform = transform
        }
    }
}

Notes

• You can add multiple gesture recognizers to a single view. For the sake of simplicity, though, I didn't do that (except for the swipe gesture). If you need to for your project, you should read the gesture recognizer documentation . It is fairly understandable and helpful.
• Known issues with my examples above: (1) Pan view resets its frame on next gesture event. (2) Swipe view comes from the wrong direction on the first swipe. (These bugs in my examples should not affect your understanding of how Gestures Recognizers work, though.)

Answer 3

I think you can simply use

UIControl *headerView = ...
[headerView addTarget:self action:@selector(myEvent:) forControlEvents:UIControlEventTouchDown];

i mean headerView extends from UIControl.

Answer 4

Swift 3 & Swift 4

import UIKit

extension UIView {
  func addTapGesture(tapNumber: Int, target: Any, action: Selector) {
    let tap = UITapGestureRecognizer(target: target, action: action)
    tap.numberOfTapsRequired = tapNumber
    addGestureRecognizer(tap)
    isUserInteractionEnabled = true
  }
}

Use

yourView.addTapGesture(tapNumber: 1, target: self, action: #selector(yourMethod))

Answer 5

Based on the accepted answer you can define a macro:

#define handle_tap(view, delegate, selector) do {\
    view.userInteractionEnabled = YES;\
    [view addGestureRecognizer: [[UITapGestureRecognizer alloc] initWithTarget:delegate action:selector]];\
} while(0)

This macro uses ARC, so there's no release call.

Macro usage example:

handle_tap(userpic, self, @selector(onTapUserpic:));

Answer 6

In Swift 4.2 and Xcode 10

Use UITapGestureRecognizer for to add touch event

//Add tap gesture to your view
let tap = UITapGestureRecognizer(target: self, action: #selector(handleGesture))
yourView.addGestureRecognizer(tap)

// GestureRecognizer
@objc func handleGesture(gesture: UITapGestureRecognizer) -> Void {
//Write your code here
}

If you want to use SharedClass

//This is my shared class
import UIKit

class SharedClass: NSObject {

    static let sharedInstance = SharedClass()

    //Tap gesture function
    func addTapGesture(view: UIView, target: Any, action: Selector) {
        let tap = UITapGestureRecognizer(target: target, action: action)
        view.addGestureRecognizer(tap)
    }
} 

I have 3 views in my ViewController called view1, view2 and view3.

override func viewDidLoad() {
    super.viewDidLoad()
    //Add gestures to your views
    SharedClass.sharedInstance.addTapGesture(view: view1, target: self, action: #selector(handleGesture))
    SharedClass.sharedInstance.addTapGesture(view: view2, target: self, action: #selector(handleGesture))
    SharedClass.sharedInstance.addTapGesture(view: view3, target: self, action: #selector(handleGesture2))

}

// GestureRecognizer
@objc func handleGesture(gesture: UITapGestureRecognizer) -> Void {
    print("printed 1&2...")
}
// GestureRecognizer
@objc func handleGesture2(gesture: UITapGestureRecognizer) -> Void {
    print("printed3...")
}

Answer 7

You can achieve this by adding Gesture Recogniser in your code.

Step 1: ViewController.m:

// Declare the Gesture.
UITapGestureRecognizer *gesRecognizer = [[UITapGestureRecognizer alloc] 
                                          initWithTarget:self 
                                          action:@selector(handleTap:)];
gesRecognizer.delegate = self;

// Add Gesture to your view.
[yourView addGestureRecognizer:gesRecognizer]; 

Step 2: ViewController.m:

// Declare the Gesture Recogniser handler method.
- (void)handleTap:(UITapGestureRecognizer *)gestureRecognizer{
   NSLog(@"Tapped");
}

NOTE: here yourView in my case was @property (strong, nonatomic) IBOutlet UIView *localView;

EDIT: *localView is the white box in Main.storyboard from below

Answer 8

Heres a Swift version:

// MARK: Gesture Extensions
extension UIView {

    func addTapGesture(#tapNumber: Int, target: AnyObject, action: Selector) {
        let tap = UITapGestureRecognizer (target: target, action: action)
        tap.numberOfTapsRequired = tapNumber
        addGestureRecognizer(tap)
        userInteractionEnabled = true
    }

    func addTapGesture(#tapNumber: Int, action: ((UITapGestureRecognizer)->())?) {
        let tap = BlockTap (tapCount: tapNumber, fingerCount: 1, action: action)
        addGestureRecognizer(tap)
        userInteractionEnabled = true
    }
}

Answer 9

Swift 3:

let tapGestureRecognizer: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(handleTapGestureRecognizer(_:)))
view.addGestureRecognizer(tapGestureRecognizer)

func handleTapGestureRecognizer(_ gestureRecognizer: UITapGestureRecognizer) {

}

Answer 10

Seems quite simple these days. This is the Swift version.

let tap = UITapGestureRecognizer(target: self, action: #selector(viewTapped))
    view.addGestureRecognizer(tap)

@objc func viewTapped(recognizer: UIGestureRecognizer)
{
    //Do what you need to do!
}

Answer 11

Objective-C:

UIControl *headerView = [[UIControl alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, nextY)];
[headerView addTarget:self action:@selector(myEvent:) forControlEvents:UIControlEventTouchDown];

Swift:

let headerView = UIControl(frame: CGRect(x: 0, y: 0, width: tableView.bounds.size.width, height: nextY))
headerView.addTarget(self, action: #selector(myEvent(_:)), for: .touchDown)

The question asks:

How do I add a touch event to a UIView?

It isn't asking for a tap event.

Specifically OP wants to implement UIControlEventTouchDown

Switching the UIView to UIControl is the right answer here because Gesture Recognisers don't know anything about .touchDown , .touchUpInside , .touchUpOutside etc.

Additionally, UIControl inherits from UIView so you're not losing any functionality.

If all you want is a tap, then you can use the Gesture Recogniser. But if you want finer control, like this question asks for, you'll need UIControl.

https://developer.apple.com/documentation/uikit/uicontrol?language=objc https://developer.apple.com/documentation/uikit/uigesturerecognizer?language=objc

Answer 12

Here is ios tapgesture; First you need to create action for GestureRecognizer after write the below code under the action as shown below

- (IBAction)tapgesture:(id)sender

{


[_password resignFirstResponder];


[_username resignFirstResponder];

NSLog(@" TapGestureRecognizer  tapped");

}

Answer 13

Another way is adding a transparent button to the view

UIButton *b = [UIButton buttonWithType:UIButtonTypeCustom];
b.frame = CGRectMake(0, 0, headerView.width, headerView.height);
[headerView addSubview:b];
[b addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchDown];

And then, handle click:

- (void)buttonClicked:(id)sender
{}

Answer 14

Create a gesture recognizer (subclass), that will implement touch events, like touchesBegan . You can add it to the view after that.

This way you'll use composition instead subclassing (which was the request).

Answer 15

Why don't you guys try SSEventListener ?

You don't need to create any gesture recognizer and separate your logic apart to another method. SSEventListener supports setting listener blocks on a view to listen for single tap gesture, double tap gesture and N-tap gesture if you like, and long press gesture. Setting a single tap gesture listener becomes this way:

[view ss_addTapViewEventListener:^(UITapGestureRecognizer *recognizer) { ... } numberOfTapsRequired:1];

Answer 16

Swift 5.3

Solution with Closure, based on: UIGestureRecognizer with closure

final class BindableGestureRecognizer: UITapGestureRecognizer {
    private var action: () -> Void

    init(action: @escaping () -> Void) {
        self.action = action
        super.init(target: nil, action: nil)
        self.addTarget(self, action: #selector(execute))
    }

    @objc private func execute() {
        action()
    }
}

public extension UIView {
    /// A discrete gesture recognizer that interprets single or multiple taps.
    /// - Parameters:
    ///   - tapNumber: The number of taps necessary for gesture recognition.
    ///   - closure: A selector that identifies the method implemented by the target to handle the gesture recognized by the receiver. The action selector must conform to the signature described in the class overview. NULL is not a valid value.
    func addTapGesture(tapNumber: Int = 1, _ closure: (() -> Void)?) {
        guard let closure = closure else { return }

        let tap = BindableGestureRecognizer(action: closure)
        tap.numberOfTapsRequired = tapNumber
        addGestureRecognizer(tap)

        isUserInteractionEnabled = true
    }
}

Using:

view.addTapGesture { [weak self] in
    self?.view.backgroundColor = .red
}