How to add UIViewController as target of UIButton action created in programmatically created UIView?

Question

I created a UIView programmatically and added a UIButton as it's subview.
I want a UIViewController to be the target of that button action.
How would I do that?
If it was created by Interface Builder then it was easy by using IBAction.

Answer 1

If you are adding the button programmatically to a subclass of UIView, then you can do it one of two ways:

1. You can make the button a property of the view, and then in the viewController that instantiates the view you can set the target of the button as follows:

   [viewSubclass.buttonName addTarget:self action:@selector(buttonTapped:) forControlEvents:UIControlEventTouchUpInside];
   

   This will set the button's target to a method of buttonTapped: in the viewController.m

2. You can create a protocol in your subview, which the parent viewController will conform to. In your view, when you add your button set it to call a method in your view. Then call the delegate method from that view so that your viewController can respond to it:

In the top your view subclass .h create the protocol:

@protocol ButtonProtocolName

- (void)buttonWasPressed;

@end

Create a property for the delegate:

@property (nonatomic, assign) id <ButtonProtocolName> delegate;

In the subclass .m set your button selector:

[button addTarget:self action:@selector(buttonTapped:) forControlEvents:UIControlEventTouchUpInside];

In the buttonTapped: method call the delegate method:

- (void)buttonTapped:(id)sender {
    [self.delegate buttonWasPressed];
}

In your viewController.h you'll need to make sure it conforms to the protocol:

@interface someViewController : UIViewController <SomeButtonProtocolName>

In your viewController.m when you init your subview, you'll have to set the delegate:

SomeView *view = ... // Init your view
// Set the delegate
view.delegate = self;

Finally, add the delegate method buttonWasPressed to the viewController.m:

- (void)buttonWasPressed {
    // Put code here for button's intended action.
}

Updated to provide Swift example

// Simple delegate protocol.
protocol SomeViewDelegate: class {
  // Method used to tell the delegate that the button was pressed in the subview.
  // You can add parameters here as you like.
  func buttonWasPressed()
}

class SomeView: UIView {
  // Define the view's delegate.
  weak var delegate: SomeViewDelegate?

  // Assuming you already have a button.
  var button: UIButton!

  // Once your view & button has been initialized, configure the button's target.
  func configureButton() {
    // Set your target
    self.button.addTarget(self, action: #selector(someButtonPressed(_:)), for: .touchUpInside)
  }

  @objc func someButtonPressed(_ sender: UIButton) {
    delegate?.buttonWasPressed()
  }
}

// Conform to the delegate protocol
class SomeViewController: UIViewController, SomeViewDelegate {
  var someView: SomeView!

  func buttonWasPressed() {
    // UIViewController can handle SomeView's button press.
  }
}

Additionally, here is a quick example using a closure instead of a delegate. (This can approach also be implemented in ObjC using blocks.)

// Use typeAlias to define closure
typealias ButtonPressedHandler = () -> Void

class SomeView: UIView {
  // Define the view's delegate.
  var pressedHandler: ButtonPressedHandler?

  // Assuming you already have a button.
  var button: UIButton!

  // Once your view & button has been initialized, configure the button's target.
  func configureButton() {
    // Set your target
    self.button.addTarget(self, action: #selector(someButtonPressed(_:)), for: .touchUpInside)
  }

  @objc func someButtonPressed(_ sender: UIButton) {
    pressedHandler?()
  }
}

class SomeViewController: UIViewController {
  var someView: SomeView!

  // Set the closure in the ViewController
  func configureButtonHandling() {
    someView.pressedHandler = {
      // UIViewController can handle SomeView's button press.
    }
  }
}