ViewController.swift

import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate {
    
    var locationManager = CLLocationManager()
    var locationStatus = CLLocationManager.authorizationStatus()
    
    @IBOutlet weak var buttonNext: UIButton!
    
    @IBAction func openPlacesView(sender: AnyObject) {
        askForLocation(sender)
    }
                            
    override func viewDidLoad() {
        super.viewDidLoad()
        locationManager.delegate = self
        setTitleForNextButton()
    }
    
    func askForLocation(sender: AnyObject) {
        if (locationStatus == CLAuthorizationStatus.Denied) {
            let url = NSURL.URLWithString(UIApplicationOpenSettingsURLString)
            UIApplication.sharedApplication().openURL(url)
        } else if (locationStatus != CLAuthorizationStatus.AuthorizedWhenInUse) {
            locationManager.requestWhenInUseAuthorization()
        } else if (locationStatus == CLAuthorizationStatus.AuthorizedWhenInUse){
            self.performSegueWithIdentifier("seguePlaceViewController", sender: sender)
        }
    }
    
    func locationManager(manager: CLLocationManager!, didChangeAuthorizationStatus status: CLAuthorizationStatus) {
        setTitleForNextButton()
    }
    
    private
    
    func setTitleForNextButton() {
        locationStatus = CLLocationManager.authorizationStatus()
        buttonNext.titleLabel?.textAlignment = NSTextAlignment.Center
        var text = "This text is shown in the button."
        if (locationStatus == CLAuthorizationStatus.Denied) {
            text = "Please, we need your location."
        } else if (locationStatus != CLAuthorizationStatus.AuthorizedWhenInUse) {
            text = "Give us your location to list the places around you"
        } else if (locationStatus == CLAuthorizationStatus.AuthorizedWhenInUse){
            text = "Let's go! :)"
        }
        buttonNext.setTitle(text, forState: UIControlState.Normal)
    }


}