iosswiftcore-datamapkitmkmapitem

How to convert MKMapItem to binary data to store in Core Data?


I am want to store MKMapItem that was previously found by MKLocalSearch in Core Data so I can show it to the user when the view loads in the future.

What I have is I have created an Entity in xcdatamodeld file and created a binaryData attribute called mapItem.

I want to encode the found MKMapItem to binary data and store it in core data.

Later I want to decode it to an MKMapItem.

I noticed that MKMapItem has an encode method that needs an NSCoder object.

I am not super familiar with NSCoding so any help will be appreciated.

I can always save the string attributes from MKMapItem in core data by creating multiple attributes for the entity, but I was wondering if there was an easy way.

Thanks!


Solution

  • I figured it out. To store the MapItem in Core Data, I used the NSKeyedArchiver. It encodes the MapItem into Data and to decode, you can use the NSKeyedUnarchiver

    func saveMapItems(_ mapItems: [MKMapItem]) {
        do {
            let data = try NSKeyedArchiver.archivedData(withRootObject: mapItems, requiringSecureCoding: false)
            let request: NSFetchRequest<RecentSearchLocation> = RecentSearchLocation.fetchRequest()
            if
                let recentLocations = try? coreDataManager.persistentContainer.viewContext.fetch(request).first,
                let location = recentLocations {
                location.mapItems = data
            } else {
                let location = RecentSearchLocation(context: coreDataManager.persistentContainer.viewContext)
                location.mapItems = data
            }
        } catch {
            print("Can't encode data: \(error)")
        }
        do {
            try coreDataManager.persistentContainer.viewContext.save()
        } catch {
            print("Error saving context \(error)")
        }
    }
    

    To decode I did this

    func readMapItems() -> [MKMapItem] {
            let request: NSFetchRequest<RecentSearchLocation> = RecentSearchLocation.fetchRequest()
            guard
                let data = try? coreDataManager.persistentContainer.viewContext.fetch(request).first?.mapItems,
                let dataToUnarchive = data else {
                    print("Cannot get mapItems from coreData data")
                    return []
            }
            do {
                guard let recentSearchLocations = try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(dataToUnarchive) as? [MKMapItem] else {
                    return []
                }
                return recentSearchLocations
            } catch {
                print("Error unarchiving mapItems, \(error)")
                return []
            }
        }