[ios] how to programmatically fake a touch event to a UIButton?

I'm writing some unit tests and, because of the nature of this particular app, it's important that I get as high up the UI chain as possible. So, what I'd like to do is programmatically trigger a button-press, as if the user had pressed the button in the GUI.

(Yes, yes -- I could just call the IBAction selector but, again, the nature of this particular app makes it important that I fake the actual button press, such that the IBAction be called from the button, itself.)

What's the preferred method of doing this?

An update to this answer for Swift

buttonObj.sendActionsForControlEvents(.TouchUpInside)

EDIT: Updated for Swift 3

buttonObj.sendActions(for: .touchUpInside)

For Xamarin iOS

btnObj.SendActionForControlEvents(UIControlEvent.TouchUpInside);

Reference

Swift 3:

self.btn.sendActions(for: .touchUpInside)

Swift 4:

self .yourButton(self)

In this case, UIButton is derived from UIControl. This works for object derived from UIControl.

I wanted to reuse "UIBarButtonItem" action on specific use case. Here, UIBarButtonItem doesn't offer method sendActionsForControlEvents:

But luckily, UIBarButtonItem has properties for target & action.

 if(notHappy){        
         SEL exit = self.navigationItem.rightBarButtonItem.action;
         id  world = self.navigationItem.rightBarButtonItem.target;
         [world performSelector:exit];
 }

Here, rightBarButtonItem is of type UIBarButtonItem.

If you want to do this kind of testing, you’ll love the UI Automation support in iOS 4. You can write JavaScript to simulate button presses, etc. fairly easily, though the documentation (especially the getting-started part) is a bit sparse.

It's handy for people who write Unit Tests without UI Tests ;-)

Swift 5 way to solve it for UIBarButtonItem, which does not have sendAction method like UIButton etc.

extension UIBarButtonItem {
    func sendAction() {
        guard let myTarget = target else { return }
        guard let myAction = action else { return }
        let control: UIControl = UIControl()
        control.sendAction(myAction, to: myTarget, for: nil)
    }
}

And now you can simply:

let action = UIBarButtonItem(title: "title", style: .done, target: self, action: #selector(doSomething))
action.sendAction()