I am using this struct to save a token in my app:
struct LocalStore {
static let userDefaults = NSUserDefaults.standardUserDefaults()
static func saveToken(token: String) {
userDefaults.setObject(token, forKey: "tokenKey")
}
static func getToken() -> String? {
return userDefaults.stringForKey("tokenKey")
}
static func deleteToken() {
userDefaults.removeObjectForKey("tokenKey")
}
}
I know that I wan overwrite existing saved object but can I save multiple objects? Like this:
static func saveToken(token: String) {
userDefaults.setObject(token, forKey: "tokenKey")
}
static func saveFirstName(firstName: String) {
userDefaults.setObject(firstName, forKey: "lastNameVal")
}
static func saveLastName(lastName: String) {
userDefaults.setObject(lastName, forKey: "firstNameVal")
}
Yes, as long as it has a different key. This is possible, however, from your example, you are saving your token object to multiple keys. There is nothing wrong with that if that is your intention.
User defaults is a form of persistent storage that can save many types of values (not just Strings).
The accepted answer is right, but I want to show another way of how to deal with NSUserDefaults in Swift.
By using computed properties instead of methods or functions, it is easy to use NSUserDefaults as the backing variable — and as all set and get operations are performed through this property, no further code is needed to ensure that the property has the correct value.
From production code:
var sorting:DiscoverSortingOrder {
set {
NSUserDefaults.standardUserDefaults().setInteger(newValue.rawValue, forKey: "DiscoverSorting")
refresh() // will trigger reloading the UI
}
get {
if let s = DiscoverSortingOrder(rawValue: NSUserDefaults.standardUserDefaults().integerForKey("DiscoverSorting")){
return s
}
return .New // Default value
}
}
Related
I have developed an ios application that allow users to edit a musical score sheet and now i'd like to implement data persistence to prevent the discarding of changes.
Reading on ios documentation i've noticed that exists different ways to improve data persistence and I believe that the best way for my application is Core Data.
Considering that my application use a lot of custom object i met a lot of problems.
I'm trying to use core data to save an entity, referred to a score sheet, composed by two attributes:
name: String
score: Array of another custom object (Measure), composed by other custom object (Score Element)
According to documentation and other q/a I've decided to use a Trasformable type on the model:
So I've declared a generic class used as trasformer for score attribute:
public class NSSecureCodingValueTransformer<T: NSSecureCoding & NSObject>: ValueTransformer {
public override class func transformedValueClass() -> AnyClass { T.self }
public override class func allowsReverseTransformation() -> Bool { true }
public override func transformedValue(_ value: Any?) -> Any? {
guard let value = value as? T else { return nil }
return try? NSKeyedArchiver.archivedData(withRootObject: value, requiringSecureCoding: true)
}
public override func reverseTransformedValue(_ value: Any?) -> Any? {
guard let data = value as? NSData else { return nil }
let result = try? NSKeyedUnarchiver.unarchivedObject(
ofClass: T.self,
from: data as Data
)
return result
}
/// The name of this transformer. This is the name used to register the transformer using `ValueTransformer.setValueTransformer(_:forName:)`
public static var transformerName: NSValueTransformerName {
let className = NSStringFromClass(T.self)
return NSValueTransformerName("DHC\(className)ValueTransformer")
}
/// Registers the transformer by calling `ValueTransformer.setValueTransformer(_:forName:)`.
public static func registerTransformer() {
let transformer = NSSecureCodingValueTransformer<T>()
ValueTransformer.setValueTransformer(transformer, forName: transformerName)
}
}
Using in this way a DHCMeasureValueTransformer as trasformer in DataModel file.
The problem is that when i save, no error occurs but when i fetch data for a new restart of application, i can fetch just the name of score sheet, while the score array it's empty, like if no elements it's been put inside (clearly, before of save, i've try to print array content, that prove that i'm working with a non empty array)
Here is the code of the save:
static func saveContext() {
let context = getContext()
do {
try context.save()
} catch {
print("error during the save.")
}
}
And here is the code of two classes of the entity object:
// DataClass
#objc(ScoreSheet)
public class ScoreSheet: NSManagedObject {
static var supportsSecureCoding: Bool {
return true
}
}
//DataProperties
extension ScoreSheet {
#nonobjc public class func fetchRequest() -> NSFetchRequest<ScoreSheet> {
return NSFetchRequest<ScoreSheet>(entityName: "ScoreSheet")
}
#NSManaged public var name: String
#NSManaged public var score: [Measure]
}
Clearly Measure class implements NSSecureCoding and method for decode and encode the object.
Here is Measure class implementation:
import Foundation
class Measure: NSObject, NSCoding, NSSecureCoding {
var elements : [ScoreElement] = []
var timeSig : TimeSignature
var clef : Clef
static var supportsSecureCoding = true
init(time : TimeSignature, clef : Clef) {
self.timeSig = time
self.clef = clef
}
func encode(with encoder: NSCoder) {
encoder.encode(self.elements, forKey: "elements")
encoder.encode(self.timeSig, forKey: "timeSig")
encoder.encode(self.clef, forKey: "clef")
}
required convenience init? (coder decoder: NSCoder) {
let elements = decoder.decodeObject(forKey: "elements") as! [ScoreElement]
let timeSig = decoder.decodeObject(forKey: "timeSig") as! TimeSignature
let clef = decoder.decodeObject(forKey: "clef") as! Clef
self.init(time: timeSig, clef: clef)
self.elements = elements
}
}
I'm not sure what's going wrong but there are a couple of things that need fixing that might affect your results.
Firstly, the computed transformer name is not the same as the one you're trying to use. When this line executes, and T is Measure,
let className = NSStringFromClass(T.self)
Then className is going to be something like MyProjectName.Measure. The computed transformer name ends up as something like NSValueTransformerName(_rawValue: DHCMyProjectName.MeasureValueTransformer), which doesn't match what you're using in the data model. All of which means that your transformer isn't getting used.
But that probably doesn't matter because if Measure conforms to NSSecureCoding and all of Measure's properties (ScoreElement, TimeSignature, Clef) also conform to NSSecureCoding (which seems to be the case since your code isn't throwing exceptions), then you don't need a custom transformer at all. If a transformable property type conforms to NSSecureCoding then Core Data will automatically use NSSecureCoding. You don't need a custom transformer unless you don't want to or can't conform to NSSecureCoding for some reason. Because of this, it doesn't matter that your transformer isn't being used.
As for why Measure isn't surviving the encode/decode process, I don't know, but you may help clear things up by removing the distraction of the unnecessary encode/decode class. I'd also suggest putting a breakpoint in Measure in the encode(with:) and init(coder:) methods. You should hit those breakpoints when saving and fetching data.
Is it possible to display as one array objects retrieved from network and same model but retrieved from core data. Purpose is to have same data possible to be public (then retrieved from network) or private and then this data is stored locally in coredata model. Attributes/Properties will be the same for both.
I plan to display this as swiftUI view (if that matters)
After some search I came with idea to have one struct that based on its privacy property will be translated to core data class model or if public directly connected to networking layer?
for example (some pseudo swift ;) )
struct Note {
let note: String
let isPrivate: Bool
func save(self) {
if self.isPrivate { save to CoreData }
else { send save request with use of networking }
}
}
class coreDataModel: NSManagedObject {
var note: String
let isPrivate = true
}
struct networkingModel {
var note: String
let isPrivate = false
}
class modelManager {
func joinData() {
let joinedModel: Note = coreDataModel + networkingModel
// and so on to display that model
}
}
I think you can try this, first load the ui with the existing local data. At the same time, make a call to your api on a background queue. Once the api results are available, filter for duplicates, then persist it locally. Then the last step is to notify the ui to reload.
This pseudo-code is a bit UIKit specific, however the same logic can be applied to when in SwiftUI. You won't need closure, you will compute directly to your publisher object, and ui will react based any new emits.
/// you can have one model for both api and core data
struct Note: Hashable { let uuid = UUID.init() }
class ModelManager {
private var _items: Array<Note> = []
var onChanged: ((Array<Note>) -> Void)? = nil
// you might also have an init, where you can have a timer running
func start() {
loadFromCoreData { [weak self] (items) in
guard let `self` = self else { return }
self._items.append(contentsOf: items)
self.onChanged?(self._items)
self.loadFromApi()
}
}
private func loadFromCoreData(completion: #escaping (Array<Note>) -> Void) {
// background queue
// logic to load from coredata.
let coreDataResults: Array<Note> = []
completion(coreDataResults)
}
private func loadFromApi() {
// background queue
let apiResults: Array<Note> = []
compute(contents: apiResults)
}
private func compute(contents: Array<Note>) {
let combined = zip(_items, contents).flatMap{[$0.0, $0.1] }
let newItems = Array(Set(combined)) // set doesn't allow duplicates
// save to db
// insert to new to _items
_items.append(contentsOf: newItems)
// sort maybe to place new items on top
self.onChanged?(self._items)
}
}
// usage of this object
let manager = ModelManager()
manager.start()
manager.onChanged = { items in
// [weak self] remember of retain cycles
// make sure you are on main queue when reloading
}
I want to create a duplicate of a persisted object such that the new instance has all the same values but is not attached to Realm. Using Object(value: persistedInstance) works great for classes whose properties are all strings, dates, numbers, etc. However, when duplicating an instance of a class with List type properties, the duplicate's List and the List's elements continue to reference the persisted records. How can I create a duplicate that's fully detached from Realm, including any Lists and elements in those Lists?
You can make a deep copy of your object via the following extension functions:
import UIKit
import Realm
import RealmSwift
protocol RealmListDetachable {
func detached() -> Self
}
extension List: RealmListDetachable where Element: Object {
func detached() -> List<Element> {
let detached = self.detached
let result = List<Element>()
result.append(objectsIn: detached)
return result
}
}
#objc extension Object {
public func detached() -> Self {
let detached = type(of: self).init()
for property in objectSchema.properties {
guard
property != objectSchema.primaryKeyProperty,
let value = value(forKey: property.name)
else { continue }
if let detachable = value as? Object {
detached.setValue(detachable.detached(), forKey: property.name)
} else if let list = value as? RealmListDetachable {
detached.setValue(list.detached(), forKey: property.name)
} else {
detached.setValue(value, forKey: property.name)
}
}
return detached
}
}
extension Sequence where Iterator.Element: Object {
public var detached: [Element] {
return self.map({ $0.detached() })
}
}
Use
/// in collections
let data = realm.objects(AbcDfg.self).detached
/// single object
data.first?.detached()
This is not yet supported natively by Realm, but a requested feature tracked by issue #3381.
For now, you would need to implement your own deep copy constructor. A common strategy is to do that on every model and call the deep copy constructors of related objects. You need to pay attention though that you don't run into cycles.
We use ObjectMapper to create a deep copy of the object by turning into JSON and then turn that JSON back into same object except it's not associated with Realm.
Mike.
As mentioned in the issue tracked at #3381, the solution for now is an implementation to create detached copies from Realm objects.
There is a better version of the detachable object implementation at
https://github.com/realm/realm-cocoa/issues/5433#issuecomment-415066361.
Incase the link doesnot work, the code by Alarson93 is:
protocol DetachableObject: AnyObject {
func detached() -> Self
}
extension Object: DetachableObject {
func detached() -> Self {
let detached = type(of: self).init()
for property in objectSchema.properties {
guard let value = value(forKey: property.name) else { continue }
if property.isArray == true {
//Realm List property support
let detachable = value as? DetachableObject
detached.setValue(detachable?.detached(), forKey: property.name)
} else if property.type == .object {
//Realm Object property support
let detachable = value as? DetachableObject
detached.setValue(detachable?.detached(), forKey: property.name)
} else {
detached.setValue(value, forKey: property.name)
}
}
return detached
}
}
extension List: DetachableObject {
func detached() -> List<Element> {
let result = List<Element>()
forEach {
if let detachable = $0 as? DetachableObject {
let detached = detachable.detached() as! Element
result.append(detached)
} else {
result.append($0) //Primtives are pass by value; don't need to recreate
}
}
return result
}
func toArray() -> [Element] {
return Array(self.detached())
}
}
extension Results {
func toArray() -> [Element] {
let result = List<Element>()
forEach {
result.append($0)
}
return Array(result.detached())
}
}
In Realm 5.0.0 freeze() method has been added.
according to release notes:
Add support for frozen objects. Realm, Results, List and Object now have freeze() methods which return a frozen copy of the object. These objects behave similarly to creating unmanaged deep copies of the source objects. They can be read from any thread and do not update when writes are made to the Realm, but creating frozen objects does not actually copy data out of the Realm and so can be much faster and use less memory. Frozen objects cannot be mutated or observed for changes (as they never change). (PR #6427).
Previously answered here
As of now, Dec 2020, there is not proper solution of this issue. We have many workarounds though.
Here is the one I have been using, and one with less limitations in my opinion.
Make your Realm Model Object classes conform to codable
class Dog: Object, Codable{
#objc dynamic var breed:String = "JustAnyDog"
}
Create this helper class
class RealmHelper {
//Used to expose generic
static func DetachedCopy<T:Codable>(of object:T) -> T?{
do{
let json = try JSONEncoder().encode(object)
return try JSONDecoder().decode(T.self, from: json)
}
catch let error{
print(error)
return nil
}
}
}
Call this method whenever you need detached / true deep copy of your Realm Object, like this:
//Suppose your Realm managed object: let dog:Dog = RealmDBService.shared.getFirstDog()
guard let detachedDog = RealmHelper.DetachedCopy(of: dog) else{
print("Could not detach Dog")
return
}
//Change/mutate object properties as you want
detachedDog.breed = "rottweiler"
As you can see we are piggy backing on Swift's JSONEncoder and JSONDecoder, using power of Codable, making true deep copy no matter how many nested objects are there under our realm object. Just make sure all your Realm Model Classes conform to Codable.
Though its NOT an ideal solution, but its one of the most effective workaround.
I use Realm Swift 0.95.3. In my project I'm working with a contact (not with contacts AddressBook), which contain information about the name, last name, middle name, email, … and photograph.
I have created a subclass of Object called Contact. I understand that the image, or any other binary data, should not be stored in the Realm. Especially as my images could be large enough ~5 Mb.
In any case, I wanted to store the image in the file system, and Realm stores only a link to this image. I thought that in the future I may need to attach other files (audio, PDF, …) to subclasses of Object. So I decided to create a separate class File, which is inherited from Object. The whole structure looks like.
class File: Object {
dynamic var objectID = NSUUID().UUIDString
private var filePath: String {
let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
let documentsDirectory = paths[0] as NSString
return documentsDirectory.stringByAppendingPathComponent(objectID)
}
lazy var fileData: NSData? = {
return self.readFile()
}()
override static func primaryKey() -> String? {
return "objectID"
}
override static func ignoredProperties() -> [String] {
return ["fileData"]
}
override func copy() -> AnyObject {
let result = File(value: self)
result.objectID = NSUUID().UUIDString
result.fileData = fileData?.copy() as? NSData
return result
}
}
extension File {
//MARK:-
private func readFile() -> NSData? {
let lFilePath = filePath
print("Try to read file \(lFilePath)")
return NSData(contentsOfFile: lFilePath)
}
private func writeFileWithFileData() {
if let lFileData = fileData {
lFileData.writeToFile(filePath, atomically: true)
print("File \(filePath) was created")
} else {
removeFile()
}
}
private func removeFile() {
do {
try NSFileManager.defaultManager().removeItemAtPath(filePath)
print("File \(filePath) was removed")
} catch {
print(error)
}
}
}
As you can see, when trying to get the property fileData, data is received from the file system. Moreover fileData is declared with the keyword lazy, that is, I wish that the data is requested from disk to cache in this property. If this property is changed, the File object before saving to the database, I call writeFileWithFileData (), and data on the disk is overwritten. This system works as I need to, I to experiment. Then I created a Contact.
class Contact: Object {
dynamic var objectID = NSUUID().UUIDString
dynamic var firstName = ""
dynamic var lastName = ""
...
private dynamic var avatarFile: File?
var avatar: UIImage? {
get {
guard let imageData = avatarFile?.fileData else { return nil }
return UIImage(data: imageData)
}
set {
avatarFile = File()
guard let imageData = newValue else {
avatarFile?.fileData = nil
return
}
avatarFile?.fileData = UIImagePNGRepresentation(imageData)
}
}
override static func primaryKey() -> String? {
return "objectID"
}
override static func ignoredProperties() -> [String] {
return ["image"]
}
}
The problem is that when I choose a contact from the database, and am trying to get the avatar, then access to the file system occurs every time you access this property. That is, property fileData does not operate as lazy - as I thought at first. But then I looked at the memory address properties avatarFile, each time it is received, the address has changed. From this I can conclude that the object avatarFile is constantly requested from the database again, with any reference to this property. As a consequence, all its ignoredProperties are reset.
Why is the relation-object reinitialized each time it is accessed?
Share your opinion about my arch
It should be fine. Realm Objects are live links to their parent Realm object, not static copies, so their addresses do periodically change. This is normal, and the objects aren't getting re-allocated so you shouldn't see any memory issues here. As far as I'm aware, NSData itself is lazy, so the data won't actually be read until you explicitly request it.
Your architecture looks good! You're right in that it's usually not the best form to store file data directly inside a Realm file, but you've done a good job at making the Realm Object manage the external file data as if it was. :)
so as the title already states I'm trying to save an array to the database. If this is possible, how do I do it? If not I hope you can help me with some other solution.
I am making an iOS app where if the user touches (and moves) the screen I store this data in an array. Because it needs to be multi-touch all the CGPoints of the touches (either touchesBegan or touchesMoved) on one moment are stored in an array, which again is stored in the main array. Resulting in var everyLocation = [[CGPoint]](). I already found out that it's not possible to store a CGPoint in a database directly, so I can convert them to string with NSStringFromCGPoint(pointVariable). This however isn't very useful as long as I can't store the array...
I want to store the date on which it happened too, so in my database I created the entity 'Locations' with two attributes: 'locations' and 'date'. In the final application the entity name will be the name of the exercise the user was doing (I have about four exercises, so four entities).
Most of the sample code I've seen stores the CGPoint either in a separate x and y or in one string. I can maybe do this too, so I don't have to store arrays. To do this I think I will have to make the attribute(s) the coordinates of the touche(s), the entity name would be the date, and the db name would be the name of the exercise. If this is the only solution, how do I create an entity (with attributes) at run-time?
Thanks in advance
Swift3 makes it seamless,
just write
typealias Point = CGPoint
and set the attribute type to Transformable and set the Custom class of it to
Array<Point>
Works for me without having to do anything.
1) add a "Transformable" type attribute.
2) Event.h
#interface Event : NSManagedObject
#property (nonatomic, retain) NSArray * absentArray;
#interface AbsentArray : NSValueTransformer
#end
Event.m
#implementation AbsentArray
+ (Class)transformedValueClass
{
return [NSArray class];
}
+ (BOOL)allowsReverseTransformation
{
return YES;
}
- (id)transformedValue:(id)value
{
return [NSKeyedArchiver archivedDataWithRootObject:value];
}
- (id)reverseTransformedValue:(id)value
{
return [NSKeyedUnarchiver unarchiveObjectWithData:value];
}
#end
3) Just use it as a normal array
Event *event = //init
event.absentArray = #[1,2,3];
[context save:nil]
Just change these code in swift.
You can understand as .swfit combine .h/.m file. Objective C has .h as header file which many properties there. .m is implication file which methods should be there.
For example:
.swift
import Foundation
import CoreData
class Event: NSManagedObject {
#NSManaged var absentArray: AnyObject
}
3) save:
let appDelegate =
UIApplication.sharedApplication().delegate as AppDelegate
let managedContext = appDelegate.managedObjectContext!
if !managedContext.save(&error) {
println("Could not save \(error), \(error?.userInfo)")
}
I finally managed to put the pieces together after William pointed me in the direction of transformables. I used this tutorial to understand how to work with this: http://jamesonquave.com/blog/core-data-in-swift-tutorial-part-1/
Here are the things I learned from going through this exercise that was prompted by the warning message:
At some point, Core Data will default to using "NSSecureUnarchiveFromData" when nil is specified, and transformable properties containing classes that do not support NSSecureCoding will become unreadable.
My app had collected the series of points [CGPoint] created by drawing on the screen with an Apple Pencil or finger and stored that in CoreData - basically the heart of a thing I called a Scribble. To store in CoreData, I created an attribute named “points” and set the type to Transformable. The Custom Class was set to [CGPoint]. Also, I set CodeGen to Manual rather than the automatic “Class Definition” option. When I generated the CoreData managed object subclass files, it generates a +CoreDataClass.swift file with the critical line of interest being:
#NSManaged public var points: [CGPoint]?
It should be noted, that there is actually a problem if you use the automatic option as the file that is generated doesn’t know what a CGPoint is and cannot be edited to add the import for UIKit for it to find the definition.
This worked fine until Apple started wanting to encourage secure coding. In the code file below, I developed a ScribblePoints object to work with the encoding and its associated data transformer.
//
// ScribblePoints.swift
//
import Foundation
import UIKit
public class ScribblePoints: NSObject, NSCoding {
var points: [CGPoint] = []
enum Key: String {
case points = "points"
}
init(points: [CGPoint]) {
self.points = points
}
public func encode(with coder: NSCoder) {
coder.encode(points, forKey: Key.points.rawValue)
}
public required convenience init?(coder: NSCoder) {
if let sPts = coder.decodeObject(of: ScribblePoints.self, forKey: Key.points.rawValue) {
self.init(points: sPts.points)
} else {
return nil
}
}
}
extension ScribblePoints : NSSecureCoding {
public static var supportsSecureCoding = true
}
#available(iOS 12.0, *)
#objc(ScribblePointsValueTransformer)
final class ScribblePointsValueTransformer: NSSecureUnarchiveFromDataTransformer {
static let name = NSValueTransformerName(rawValue: String(describing: ScribblePointsValueTransformer.self))
override static var allowedTopLevelClasses: [AnyClass] {
return [ScribblePoints.self]
}
public static func register() {
let transformer = ScribblePointsValueTransformer()
ValueTransformer.setValueTransformer(transformer, forName: name)
}
override class func allowsReverseTransformation() -> Bool {
return true
}
override func transformedValue(_ value: Any?) -> Any? {
if let data = value as? Data {
// Following deprecated at iOS12:
// if let data = value as? Data {
// if let points = NSKeyedUnarchiver.unarchiveObject(with: data) as? [CGPoint] {
// return points
// }
// }
do {
let unarchiver = try NSKeyedUnarchiver(forReadingFrom: data)
unarchiver.requiresSecureCoding = false
let decodeResult = unarchiver.decodeObject(of: [NSArray.self, ScribblePoints.self], forKey: NSKeyedArchiveRootObjectKey)
if let points = decodeResult as? [CGPoint] {
return points
}
} catch {
}
}
return nil
}
override func reverseTransformedValue(_ value: Any?) -> Any? {
if let points = value as? [CGPoint] {
// Following deprecated at iOS12:
// let data = NSKeyedArchiver.archivedData(withRootObject: points)
// return data
do {
let data = try NSKeyedArchiver.archivedData(withRootObject: points, requiringSecureCoding: true)
return data
} catch {
}
}
return nil
}
}
With the above in place, I could finally fill in ScribblePointsValueTransformer for the Transformer name for the “points” attribute in CoreData.
One can also switch the Custom Class from [CGPoint] to ScribblePoints. This doesn’t appear to affect code execution. However, if you re-generate the +CoreDataClass.swift file, the critical line of interest will become:
#NSManaged public var points: ScribblePoints?
and when you re-compile you will have code changes to make to deal with the different definition. If you were starting from scratch, it seems you may want to simply use the ScribblePoints definition, and avoid the hassles of dealing with NSArrays and NSPoints and other stuff you magically encounter in strange ways with [CGPoint].
Above was with Swift 5.
Ran into a warning message with my answer above when I hooked up an older iOS device (iOS9) to Xcode. Things worked, but the warning message about not finding the value transformer was disturbing. The problem was that the previous answer only defined and registered the value transformer if you were on iOS12+. To work without complaint on earlier systems, one needs to avoid the NSSecureUnarchiveFromDataTransformer, use ValueTransformer instead, and rely on the NSSecureCoding conformance for your coding object. Then you can register your value transformer on older iOS systems. It should also be noted that the transformedValue() and reverseTransformedValue() functions became reversed.
The net result is the following code instead.
//
// ScribblePoints.swift
//
import Foundation
import UIKit
public class ScribblePoints: NSObject, NSCoding {
var points:[CGPoint] = []
enum Key: String {
case points = "points"
}
init(points: [CGPoint]) {
self.points = points
}
public func encode(with coder: NSCoder) {
coder.encode(points, forKey: Key.points.rawValue)
}
public required convenience init?(coder: NSCoder) {
if let sPts = coder.decodeObject(of: ScribblePoints.self, forKey: Key.points.rawValue) {
self.init(points: sPts.points)
} else {
return nil
}
}
}
extension ScribblePoints : NSSecureCoding {
public static var supportsSecureCoding = true
}
#objc(ScribblePointsValueTransformer)
final class ScribblePointsValueTransformer: ValueTransformer {
static let name = NSValueTransformerName(rawValue: String(describing: ScribblePointsValueTransformer.self))
public static func register() {
let transformer = ScribblePointsValueTransformer()
ValueTransformer.setValueTransformer(transformer, forName: name)
}
override class func transformedValueClass() -> AnyClass {
return ScribblePoints.self
}
override class func allowsReverseTransformation() -> Bool {
return true
}
override func reverseTransformedValue(_ value: Any?) -> Any? {
if let data = value as? Data {
do {
if #available(iOS 11.0, *) {
let unarchiver = try NSKeyedUnarchiver(forReadingFrom: data)
unarchiver.requiresSecureCoding = false
let decodeResult = unarchiver.decodeObject(of: [NSArray.self, ScribblePoints.self], forKey: NSKeyedArchiveRootObjectKey)
if let points = decodeResult as? [CGPoint] {
return points
}
} else {
// Fallback on earlier versions
if let data = value as? Data {
if let points = NSKeyedUnarchiver.unarchiveObject(with: data) as? [CGPoint] {
return points
}
}
}
} catch {
}
}
return nil
}
override func transformedValue(_ value: Any?) -> Any? {
if let points = value as? [CGPoint] {
do {
if #available(iOS 11.0, *) {
let data = try NSKeyedArchiver.archivedData(withRootObject: points, requiringSecureCoding: true)
return data
} else {
// Fallback on earlier versions
let data = NSKeyedArchiver.archivedData(withRootObject: points)
return data
}
} catch {
}
}
return nil
}
}
In CoreData, the way things are defined is shown below.