I am trying to define a wrapper around objects I want to store in Realm. The wrapper should contain an additional date object so that I can filter old objects. So far I have this
public final class RealmDateTaggedRealmObject: ObjectFacade {
#objc public dynamic var date: Date?
#objc public dynamic var value: ObjectFacade?
#objc private dynamic var id: String = ""
public override class func primaryKey() -> String? {
return #keyPath(id)
}
public convenience init<T: RealmMappable>(from object: RealmDateTagged<T>) {
self.init()
date = object.date
value = object.value.asRealmObject
id = object.primaryKey
}
}
The RealmMappable protocol enables transforming implementing entities into ObjectFacade. The ObjectFacade class is an empty class that inherits from Object, because I got an exception if I declared
#objc public dynamic var value: Object?
So I tried to be smart and created ObjectFacade. Turns out I'm not so smart cause it always stores nil. Also, value can't be a generic type because it is not supported in Objective-C.
Any suggestions?
Thanks!
Related
I may be simply understanding this incorrectly, but when I created an Exercise entity and looked at it contents in the debugger I get this repeating reference to the Entity type.
The Exercise+CoreDataProperties file is standard:
import Foundation
import CoreData
extension Exercise {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Exercise> {
return NSFetchRequest<Exercise>(entityName: "Exercise")
}
#NSManaged public var exerciseDuration: Int16
#NSManaged public var repeatNo: Int16
#NSManaged public var restDuration: Int16
#NSManaged public var exerciseName: String
#NSManaged public var id: UUID
#NSManaged public var associatedWorkout: NSSet?
}
// MARK: Generated accessors for associatedWorkout
extension Exercise {
#objc(addAssociatedWorkoutObject:)
#NSManaged public func addToAssociatedWorkout(_ value: WorkoutSet)
#objc(removeAssociatedWorkoutObject:)
#NSManaged public func removeFromAssociatedWorkout(_ value: WorkoutSet)
#objc(addAssociatedWorkout:)
#NSManaged public func addToAssociatedWorkout(_ values: NSSet)
#objc(removeAssociatedWorkout:)
#NSManaged public func removeFromAssociatedWorkout(_ values: NSSet)
}
extension Exercise : Identifiable {
}
And here is the xcdatamodeld config:
Any ideas why I cannot view the values of the object in debug mode once I've created it? Have I done something in my code to cause this repetition?
The variables view you're using can't see into the values of properties of managed objects (or of most objects). If you want to inspect the property values, use the debug console. When you're stopped on the line in your screenshot, you should be able to use po newExercise to see properties of newExercise, or you can use commands like po newExercise.exerciseName to see individual property values.
I'm storing data in a CoreData entity that uses relationships. By default a toMany type relationship will be of typeNSSet. In order to load this NSSet into a tableview in the order in which the items where added to this NSSet I need to convert it to an array. How do I go about achieving this?
NSManaged Subclass generated:
extension Node {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Node> {
return NSFetchRequest<Node>(entityName: "Node")
}
#NSManaged public var value: String?
#NSManaged public var children: NSSet?
#NSManaged public var parent: Node?
#objc(addChildrenObject:)
#NSManaged public func addToChildren(_ value: Node)
#objc(removeChildrenObject:)
#NSManaged public func removeFromChildren(_ value: Node)
#objc(addChildren:)
#NSManaged public func addToChildren(_ values: NSSet)
#objc(removeChildren:)
#NSManaged public func removeFromChildren(_ values: NSSet)
}
Note: As CloudKit doesn't support ordered relationships, I can't use ordered arrangement as a part of the solution.
My suggestion is to declare the relationship as non-optional native Swift type
#NSManaged public var children: Set<Node>
To get an array just sort the set. This is pretty easy with a Swift Set. As a set is unordered by definition you have to do that anyway to get a fixed order. Assuming you have a dateAdded attribute you can write
let sortedChildren = children.sorted{$0.dateAdded > $1.dateAdded}
I have generated classes for two core data entities. The first is called Address and is an abstract entity. The second is called Person, and it inherits from Address. I've added a few example managed attributes for the purpose of this test. And i've added a non-managed String property to the Person class. Accessing the string property of the Person class will crash. Why does this crash?
The Address and Person classes are automatically generated by Xcode, with the exception of the extra parameter: let foo = "Foo"
If i modify the code to make Person inherit from NSManagedObject directly instead of Address, then the code works and doesn't crash.
Automatically generated Address class:
#objc(Address)
public class Address: NSManagedObject {
}
extension Address {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Address> {
return NSFetchRequest<Address>(entityName: "Address")
}
#NSManaged public var street: String?
#NSManaged public var city: String?
}
Automatically generated person class with the exception of the "foo" parameter:
#objc(Person)
public class Person: Address {
public let foo = "Foo" //added this parameter
}
extension Person {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Person> {
return NSFetchRequest<Person>(entityName: "Person")
}
#NSManaged public var name: String?
}
problem code
let person = Person(context: context)
print(person.foo) //doesn't crash, but prints empty line instead of value
print("VALUE:\(person.foo):") //crashes with Thread 1: EXC_BAD_ACCESS (code=1, address=0x18)
UPDATE:
if foo is defined as
public let foo: String? = "Foo"
then the print statements don't crash, instead they interpret the value as 'nil' and print that.
So my question becomes: Why is this value which is assigned as a constant being reset to nil under the covers?
I have two hand-waving explanations why you are getting nil:
Managed objects don't function very well until they are inserted.
Your foo is a what I would call a constant stored property. I made up the name because, red flag, I cannot find any examples of it in the Swift book chapter on Properties
Put these two together and you get an edge case that doesn't work.
That being said, I'm kind of surprised that your foo setting does not work, because foo is not a managed property (that is, it is not in the data model). If I make such a constant stored property in a regular, non-managed object…
public class Animal {
public let foo: String! = "Foo"
}
it reads back later as expected.
So, if you can accept that this edge case just doesn't work in Core Data, you can move on to several more normal ways that do work.
One way is to declare foo as a var and assign a value to in awakeFromInsert() which is, as I alluded to earlier, after insertion. In Core Data, awakeFromInsert() is one of your friends…
#objc(Person)
public class Person: Address {
public var foo: String!
override public func awakeFromInsert() {
foo = "Foo"
}
}
Another way that works is as a computed property…
#objc(Person)
public class Person: Address {
public var foo : String { return "Foo" }
}
And, finally, the most logical way, since foo is constant for all instances, is to make it a type property…
#objc(Person)
public class Person: Address {
static var foo: String = "Foo"
}
but of course if you do this you must reference it as Person.foo instead of person.foo.
I'm using a custom base class for my models to be used with Realm for Swift. This is the class.
import RealmSwift
public class ModelBase: Object {
#objc public var createdAt, updatedAt: Date
required convenience init() {
createdAt = Date()
updatedAt = Date()
self.init()
}
}
Now, when trying to compile this, Xcode will throw an error
Class 'ModelBase' has not initializers
However, when I change the initializer function to required public init() and then let it call super.init(), Realm will start complaining that I need to implement additional initializers. Anyone know how I can fix the first issue?
You need to use custom initializer with declared init parameters, like this:
import RealmSwift
public class ModelBase: Object {
#objc public dynamic var createdAt, updatedAt: Date
convenience init(_ defaultDate: Date = Date()) {
self.init()
createdAt = defaultDate
updatedAt = defaultDate
}
}
in convenience init self.init() has to be called before initializing all other properties. Also you need to declare properties as dynamic since theirs getters and setters are managed by Realm itself.
or if createdAt and updatedAt are Date() by default you can omit initializer at all by declaring vars in class declaration.
public class ModelBase: Object {
#objc public dynamic var createdAt: Date = Date()
#objc public dynamic var updatedAt: Date = Date()
}
I have a core data project that includes the following NSManagedObjects:
********************** FSDJump NSManaged Object
extension FSDJump {
#nonobjc public class func fetchRequest() -> NSFetchRequest<FSDJump> {
return NSFetchRequest<FSDJump>(entityName: "FSDJump")
}
#NSManaged public var starSystem: String
#NSManaged public var starPos: NSArray
#NSManaged public var bodyName: String
#NSManaged public var jumpDist: Float
#NSManaged public var fuelUsed: Float
#NSManaged public var fuelLevel: Float
#NSManaged public var boostUsed: Bool
#NSManaged public var systemFaction: String
#NSManaged public var systemAllegiance: String
#NSManaged public var systemEconomy: String
#NSManaged public var systemGoverment: String
#NSManaged public var systemSecurity: String
#NSManaged public var powers: NSArray
#NSManaged public var powerplayState: String
#NSManaged public var timeStamp: String
#NSManaged public var factionState: String
#NSManaged public var factions: NSSet
}
// MARK: Generated accessors for factions
extension FSDJump {
#objc(addFactionsObject:)
#NSManaged public func addToFactions(_ value: Factions)
#objc(removeFactionsObject:)
#NSManaged public func removeFromFactions(_ value: Factions)
#objc(addFactions:)
#NSManaged public func addToFactions(_ values: NSSet)
#objc(removeFactions:)
#NSManaged public func removeFromFactions(_ values: NSSet)
}
********************** Factions NSManaged Object
extension Factions {
#nonobjc public class func fetchRequest() -> NSFetchRequest<Factions> {
return NSFetchRequest<Factions>(entityName: "Factions")
}
#NSManaged public var name: String
#NSManaged public var allegiance: String
#NSManaged public var factionState: String
#NSManaged public var government: String
#NSManaged public var influence: Float
#NSManaged public var fsdJump: FSDJump
}
with a one to many relationship defined between FSDJump and Factions (i.e. one FSDJump may have multiple factions (with the inverse relationship defined as 'fsdJump').
I use the following code to save multiple Factions (where they exist) within an 'if else' statement saves each fsdJumpEvent.
if fsdJumpEvent["Factions"].exists() {
// save all of the Faction array objects in the variable arrayOfFactions
let arrayOfFactions = fsdJumpEvent["Factions"]
// create a newFaction managedObject to save the faction details to
let newFaction = (Factions(context: contextTCCEDJ))
for faction in arrayOfFactions {
// the following is strictly not necesary but it makes the code easier to read
// first allocate the values from faction to a local variable then allocate that variable to the newFaction managedObject
// Note faction is a tuple (string, JSON) so the construct 'faction.1' accesses the second value in the tuple
// 'faction.0' would access the first value in the tuple which is the array index "0", "1", "2", etc
let newFactionName = faction.1["Name"].string!
let newFactionState = faction.1["FactionState"].string!
let newFactionGovernment = faction.1["Government"].string!
let newFactionAllegiance = faction.1["Allegiance"].string!
let newFactionInfluence = faction.1["Influence"].float!
newFaction.name = newFactionName
newFaction.allegiance = newFactionAllegiance
newFaction.government = newFactionGovernment
newFaction.influence = newFactionInfluence
newFaction.factionState = newFactionState
// Add the new object to the context allowing it to be saved.
fsdJump.addToFactions(newFaction)
print("Faction added \(newFaction)")
}
}
The code appears to work. It builds, it runs and the print("Faction added \(newFaction)") statement prints multiple Factions per FSDJump as expected when they exist and as per the source data file I am using (JSON).
I can fetch the results and display them in a NSTableView. I can load data without any problems for the FSDJump managed object and display that in a NSTableView.
The fetch code is:
// Function returns all of the Factions associated with the timeStamp related entry in FSDJumps using the fsdJump relationship
func eventFactionsFetchSavedDataFromPersistenStore (contextTCCEDJ: NSManagedObjectContext, timeStamp: String) -> [Factions] {
var result = Array<Factions>()
let localFetchRequest = Factions.fetchRequest() as NSFetchRequest
localFetchRequest.predicate = NSPredicate(format:"fsdJump.timeStamp == '\(timeStamp)'")
do {
result = try contextTCCEDJ.fetch(localFetchRequest)
} catch {
print("Error in returning Factions event saved data from the persistent store")
}
print(result.count)
for reSult in result {
print(reSult.fsdJump.timeStamp)
}
return result
}
However, it only seems to save the last 'faction' for each relationship - rather than the multiple factions that are shown in the for faction in arrayOfFactions loop. Because the fetch statement only returns one Faction per fetch. Even if I remove the predicate statement it returns all of the saved factions but again only one has been saved per fsdJumpEvent instead of the multiple factions that are identified by the print statement.
I have tried everything I can think of. I have not been able to find a previous question that relates to this specific issue.
Am I using the 'addToFactions' function incorrectly?
Any help would be gratefully received.
(And yes - for any Elite Dangerous fans out there I am writing a macOS app to parse my journal files as a companion app to my windows version of Elite Dangerous.)
You are creating a new, single instance of newFaction outside of your for faction in arrayOfFactions loop. So that single newFaction is used each time the loop runs and just assigns new values to it (overwriting previous values) resulting in it ending up with the last set of values. Hence you seeing a single faction with the 'last' set of values. Move the line:
Let newFaction = Factions(context: contectTCCEDJ)
Inside (at the beginning) of the for in loop.
Edit: you are adding your faction to a Set (which by definition requires unique entities) so all you're currently doing is re-adding the same faction each time rather than a new one. To-many relationships point to a Set.