Unrecognized Selector swift : <p>I've perused the previous posts on SO regarding this topic and I've ensured my code doesn't contain the same bugs, but I keep getting the error "Unrecognized selector sent to instance" when I try tap my UIButton. Can anyone figure out what the issue is? I've made sure that both my action name and signature are identical to the function I'm connecting to my button. I've tried restarting XCode and it still doesn't work. Any input is appreciated. </p>

<pre><code>import UIKit
import MapKit

class MapViewController: UIViewController {

    var mapView: MKMapView!

    override func loadView() {

        //create an instance of the MkMapView class and set it as the view controllers view
        mapView = MKMapView ()
        view = mapView

        //create a set of segmented controls to the map interface to give the user some options regarding their map 
        let segmentedControls = UISegmentedControl(items: ["Satellite", "Standard", "Hybrid"])

        //set the color of the segemented controls and set which index they default to on launch
        segmentedControls.backgroundColor = UIColor.whiteColor().colorWithAlphaComponent(0.5)
        segmentedControls.selectedSegmentIndex = 0

        //how auto-layout used to work was each view would have an auto-resizing mask that iOS would look at and add constraints onto the view based on its mask. The problem is now that we can manually add constraints ourselves, we run into conflicts in the layout between the constraints we set out and those iOS sets up itself through the mask. The best way to avoid this is to simply set the translatesAutoreszing... property to "false" so that iOS doesn't create its own constraints and only ours get set in the project
        segmentedControls.translatesAutoresizingMaskIntoConstraints = false

        //add the segmentedControl to the main view
        view.addSubview(segmentedControls)

        //use the view margins to set the insets of the segmented controls- that way they'll adapt to the margins of whatever screen the ap loads on
        let margins = view.layoutMarginsGuide

        //create a set of constraints for the segmented controls
        let topConstraint = segmentedControls.topAnchor.constraintEqualToAnchor(topLayoutGuide.bottomAnchor, constant: 8)
        let leadConstraint = segmentedControls.leadingAnchor.constraintEqualToAnchor(margins.leadingAnchor)
        let traiConstraint = segmentedControls.trailingAnchor.constraintEqualToAnchor(margins.trailingAnchor)

        //activate the constraints
        topConstraint.active = true
        leadConstraint.active = true
        trailConstraint.active = true

        //create a UIButton, set its label, and add it to the view hierarchy
        let button = UIButton(type: .System)
        button.setTitle("Show Location", forState: .Normal)
        button.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(button)

        //create constraints and set them to active
        let buttonBottomConstraint = button.bottomAnchor.constraintEqualToAnchor(bottomLayoutGuide.topAnchor)
        let buttonLeadConstraint = button.leadingAnchor.constraintEqualToAnchor(margins.leadingAnchor)
        let buttonTrailConstraint = button.trailingAnchor.constraintEqualToAnchor(margins.trailingAnchor);

        buttonBottomConstraint.active = true
        buttonLeadConstraint.active = true
        buttonTrailConstraint.active = true

        //set the action-target connection
        button.addTarget(self, action: "zoomToUser:", forControlEvents: UIControlEvents.TouchUpInside)

        func zoomToUser(sender: UIButton!) {
            mapView.showsUserLocation = true
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        print("Loaded map view")

    }
}
</code></pre>
