搜索回到原始地图后，注释图钉会重置（Mapkit Swift）

Question

I am using MapKit's local search feature to populate a bunch of pin annotations based on a user's search. When you click on a pin, in the callout you go to a detail viewcontroller of the location. When the user segues and clicks the back button on the toolbar from the detailviewcontroller to the previous viewcontroller, all the annotation pins are gone. Is there any way to avoid this?

here is my code for the localsearch:

@IBAction func returnText(sender: AnyObject) {
    sender.resignFirstResponder();
    attractionsMap.removeAnnotations(attractionsMap.annotations);
    performSearch();
}
func performSearch() {


    matchingItems.removeAll()

    let request = MKLocalSearchRequest()
    request.naturalLanguageQuery = searchText.text;

    request.region = attractionsMap.region;

    let search = MKLocalSearch(request: request)

    search.startWithCompletionHandler({(response:
        MKLocalSearchResponse!,
        error: NSError!) in

        if error != nil {
            println("Error occured in search: \(error.localizedDescription)")
        } else if response.mapItems.count == 0 {
            println("No matches found")
        } else {
            println("Matches found")

            for item in response.mapItems as! [MKMapItem] {
                println("Name = \(item.name)")
                println("Phone = \(item.phoneNumber)")

                matchingItems.append(item as MKMapItem)
                println("Matching items = \(matchingItems.count)")

                var placemark = item.placemark;
                var subThoroughfare:String = "";
                var thoroughfare:String = "";
                var locality:String = "";
                var postalCode:String = "";
                var administrativeArea:String = "";
                var country:String = "";
                var title = "";
                var subtitle = "";

                if (placemark.subThoroughfare != nil) {
                    subThoroughfare = placemark.subThoroughfare;
                }
                if(placemark.thoroughfare != nil) {
                    thoroughfare = placemark.thoroughfare;
                }
                if(placemark.locality != nil) {
                    locality = placemark.locality;
                }
                if(placemark.postalCode != nil) {
                    postalCode = placemark.postalCode;
                }
                if(placemark.administrativeArea != nil) {
                    administrativeArea = placemark.administrativeArea;
                }
                if(placemark.country != nil) {
                    country = placemark.country;
                }
                println("viewcontroller placmark data:");
                println(locality);
                println(postalCode);
                println(administrativeArea);
                println(country);

                title = " \(subThoroughfare) \(thoroughfare) \n \(locality), \(administrativeArea) \n \(postalCode)\(country)";
                subtitle = " \(subThoroughfare) \(thoroughfare)";
                println(title);

                var annotation = MKPointAnnotation()
                annotation.coordinate = item.placemark.coordinate
                annotation.title = item.name + " " + subtitle;
                self.attractionsMap.addAnnotation(annotation)
            }
        }
    })
}

I then pass the placemark of the matching items through this method...

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    var attractionsDetailViewController:AttractionsDetailViewController = segue.destinationViewController as! AttractionsDetailViewController
    attractionsDetailViewController.attractionLocation = indicatedMapItem;
}

ANy help would be greatly appreciated.

Answer 1

You can make use of NSUserDefaults , "used to determine an application's default state". Have a look at: https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/