Passing data with prepareForSegue doesn't work - swift

Question

I am using the MapKit and when you click on an annotation balloon you get directed to another view. The function I am using for this is:
func mapView(mapView: MKMapView!, annotationView: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
//get tag here
if(annotationView.tag == 0){
//Do for 0 pin
}
if control == annotationView.rightCalloutAccessoryView {
performSegueWithIdentifier("mapToCity", sender: self)
}
}
But the problem is that I can't pass the marker data to the next view. I tried using this function in the first view but I don't exactly know how to retrieve the data in the next view or if it is even saved in "CityDetails":
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "mapToCity") {
var yourNextViewController = (segue.destinationViewController as! CityDetails)
}
}
In the second viewcontroller this:
println(CityDetails);
Only returns the location of CityDetails which is in my case Ontdek_Polen.CityDetails

Answer 1

If you want to use segue to pass data from one view to another view then use this code:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "mapToCity") {
var yourNextViewController = segue.destinationViewController as! CityDetails
yourNextViewController.foo = "This is passed"
}
}
In your destination view don't forget to create an instance which will hold this value like this:
import UIKit
class CityDetails: UIViewController {
var foo = "" //this will hold your value
override func viewDidLoad() {
super.viewDidLoad()
println(foo) //This is passed
}
}
Don't forget to set the type of your instance in next view same as you want to pass from previous view.
And one more way to pass data from one view to another view is you can use NSUserDefaults as shown in below example:
func mapView(mapView: MKMapView!, annotationView: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
//get tag here
if(annotationView.tag == 0){
//Do for 0 pin
}
if control == annotationView.rightCalloutAccessoryView {
//set your object here
NSUserDefaults.standardUserDefaults().setObject("abcd", forKey: "yourKey")
performSegueWithIdentifier("mapToCity", sender: self)
}
}
This will store this value into disk so you can read this value anywhere into your project with yourKey.
This way you can read value from NSUserDefault:
import UIKit
class CityDetails: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let foo1 = NSUserDefaults.standardUserDefaults().objectForKey("yourKey") as! String
println(foo1) //abcd
}
}
And for more Info check THIS sample project where I am passing value with segue.
Hope this will help.

Answer 2

There is no reason to use the code (segue.destinationViewController as! CityDetails).
What I would recommend doing is instead of using the last bit of code to access the destination view controllers items just create an instance of the class and access its variables and data through dot notation.
ex. (in this example I am saying that the name of the destination vc is CityDetails)
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "mapToCity") {
var yourNextViewController: CityDetails = CityDetails()
yourNextViewController.variable = 0 //example
}
}