Why is the app crashing when doing a Fetch Request in Core Data - swift

Question

Core Data is crashing when doing a fetch request but I can't understand why. The error is suggesting EXC_BAD_ACCESS but it doesn't always occur for this particular fetch request. Basically when I zoom in and out on the mapView (MKMapKit), it's at that point it crashes.
For my mapView I use the following code:
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
let userStatus = CoreDataUserLocationManagement().returnUsersLastKnownStatus()
if (annotation is MKUserLocation) && userStatus != 3 {
As you can see from the above, this is when I request the lastKnownStatus, but as mentioned it doesn't always crash.
This fetch crashes here
func returnUsersLastKnownStatus() -> Int16 {
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "UsersLocationDetails")
do {
if let fetchResults = try managedObjectContext.fetch(fetchRequest) as? [UsersLocationDetails] {
if fetchResults.count != 0 {
let managedObject = fetchResults[0]
return managedObject.lastKnownStatus
}
}
}
catch {
print("Catch error retrieving last known status to Core Data")
}
return 3
}
The log is:
Printing description of fetchRequest:
(NSFetchRequest) fetchRequest = 0x0000000283a5be20 {
baseNSPersistentStoreRequest#0 = {
baseNSObject#0 = {
isa = NSFetchRequest
}
_affectedStores = 0x0000000000000000
}
_groupByProperties = 0x0000000000000000
_havingPredicate = 0x0000000000000000
_additionalPrivateIvars = 0x0000000281044100
_valuesToFetch = 0x0000000000000000
_entity = 0x0000000282684dc0 {
baseNSObject#0 = {
isa = NSEntityDescription
}
_cd_rc = 12
_snapshotClass = 0x000000028208a760
_versionHashModifier = 0x0000000000000000
_versionHash = some {
some = 0x0000000102faea90 {
baseNSData#0 = {
baseNSObject#0 = {
isa = _PFEncodedData
}
}
_aData = some {
some = 0x00000002811c7e60 {
baseNSData#0 = {
baseNSObject#0 = {
isa = _PFVMData
}
}
_cd_rc = 1732
_length = 40944
_payload = 0x0000000102fac000
}
}
_byteCount = 32
_reserved = 0
}
}
_model = some {
some = 0x00000002832a9400 {
baseNSObject#0 = {
isa = NSManagedObjectModel
}
_dataForOptimization = some {
some = 0x00000002811c7e60 {...}
}
_optimizationHints = 0x0000000102fb5850
_additionalPrivateIvars = 0x00000002811c0120
_entities = some {
some = 0x000000028239f9f0 {
baseNSKnownKeysDictionary1#0 = {
baseNSKnownKeysDictionary#0 = {
baseNSMutableDictionary#0 = {
NSDictionary = {
NSObject = {
isa = NSKnownKeysDictionary2
}
}
}
}
_cd_rc = 0
_count = 14
_keySearch = some {
some = 0x0000000102faeb10 {
baseNSKnownKeysMappingStrategy1#0 = {
baseNSKnownKeysMappingStrategy#0 = {
baseNSObject#0 = {
isa = NSKnownKeysMappingStrategy2
}
}
_cd_rc = -2128839072
_reserved64 = 2
_table = 0x0000000102faeb40
_length = 14
_reserved1 = 0x0000000000000000
_keys = 0x0000000102faec28
}
}
}
_values = {}
}
}
}
_configurations = 0x00000002811c0100 1 key/value pair
_fetchRequestTemplates = 0x0000000000000000
_versionIdentifiers = 0x00000002811c0140 1 element
}
}
_classNameForEntity = some {
some = 0x0000000102fad388 {
base_PFAbstractString#0 = {
baseNSString#0 = {
baseNSObject#0 = {
isa = _PFEncodedString
}
}
}
_cd_rc = 0
_length = 20
_sourceData = some {
some = 0x00000002811c7e60 {...}
}
}
}
_instanceClass = 0x00000002835b9b70
_name = some {
some = 0x0000000102fad388 {...}
}
_rootentity = 0x0000000282684dc0 {...}
_superentity = 0x0000000000000000
_subentities = 0x0000000000000000
_properties = some {
some = 0x00000002835b8720 {
baseNSKnownKeysDictionary1#0 = {
baseNSKnownKeysDictionary#0 = {
baseNSMutableDictionary#0 = {
NSDictionary = {
NSObject = {
isa = NSKnownKeysDictionary2
}
}
}
}
_cd_rc = 0
_count = 9
_keySearch = some {
some = 0x0000000102fb0bf0 {
baseNSKnownKeysMappingStrategy1#0 = {
baseNSKnownKeysMappingStrategy#0 = {
baseNSObject#0 = {
isa = NSKnownKeysMappingStrategy2
}
}
_cd_rc = -2128839072
_reserved64 = 2
_table = 0x0000000102fb0c20
_length = 9
_reserved1 = 0x0000000000000000
_keys = 0x0000000102fb0cd0
}
}
}
_values = {}
}
}
}
_propertyMapping = some {
some = 0x0000000102fb0bf0 {...}
}
_userInfo = 0x0000000000000000
_flattenedSubentities = 0x0000000281ff60d0 1 element
_kvcPropertyAccessors = 0x00000002832a92c0
_modelsReferenceIDForEntity = 13
}
_predicate = 0x0000000000000000
_sortDescriptors = 0x0000000000000000
_batchSize = 0
_fetchLimit = 0
_allocationSize = 0
_relationshipKeyPathsForPrefetching = 0x0000000000000000
}
Also just noticed this in Xcode:
(NSPersistentStoreRequest) CoreData.NSPersistentStoreRequest = <parent failed to evaluate: invalid load address>

Answer 1

So it turns out that it was this piece of code that code that was causing the issue. I have no idea why as the crash wasn't reporting this but as soon as I commented it out, it no longer crashes.
#IBAction func centerUserBtnTapped(_ sender: Any) {
let location = CLLocationCoordinate2D(latitude: locationManager.location?.coordinate.latitude ?? 0.0, longitude: locationManager.location?.coordinate.longitude ?? 0.0)
let span = MKCoordinateSpan.init(latitudeDelta: self.mapView.region.span.latitudeDelta, longitudeDelta: self.mapView.region.span.longitudeDelta)
let region = MKCoordinateRegion(center: location, span: span)
self.mapView.setRegion(region, animated: true)
self.mapView.setUserTrackingMode(.follow, animated: true)
}
Instead I simplified it to the normal approach:
#IBAction func centerUserBtnTapped(_ sender: Any) {
mapView.setUserTrackingMode(.follow, animated: true)
}