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I am storing a transformable in CoreData and am trying to make it NSSecureCoding compliant, but I keep getting Unexpectedly found nil whilst unwrapping an optional value, when I try to decode

in the XCDataModel, I am set the property as transformable and use the custom class AssignedExerciseObjects, I have also set the transformer to AssignedExerciseObjectsValueTransformer

I have also registered the transformer in my CoreData stack

here is a copy of my transformer

@objc(AssignedExerciseObjectsValueTransformer)
final class AssignedExerciseObjectsValueTransformer: NSSecureUnarchiveFromDataTransformer {


static let name = NSValueTransformerName(rawValue: String(describing: AssignedExerciseObjectsValueTransformer.self))


override static var allowedTopLevelClasses: [AnyClass] {
    return [NSArray.self, AssignedExerciseObjects.self]
}

/// Registers the transformer.
public static func register() {
    let transformer = AssignedExerciseObjectsValueTransformer()
    ValueTransformer.setValueTransformer(transformer, forName: name)
}
}

and here is a copy of my custom class

import Foundation

public class AssignedExerciseObjects: NSObject, NSSecureCoding {

public static var supportsSecureCoding: Bool = true

public var assignedExerciseObjects: [AssignedExerciseObject] = []

enum Key:String {
    case assignedExerciseObjects = "assignedExerciseObjects"
}

init(assignedExerciseObjects: [AssignedExerciseObject]) {
    self.assignedExerciseObjects = assignedExerciseObjects
}

public func encode(with aCoder: NSCoder) {
    aCoder.encode(assignedExerciseObjects, forKey: Key.assignedExerciseObjects.rawValue)
}

public required convenience init?(coder aDecoder: NSCoder) {
    
    
    let mAssignedExerciseObjects = aDecoder.decodeObject(of: NSArray.self, forKey: Key.assignedExerciseObjects.rawValue) as! [AssignedExerciseObject]
 
   
    self.init(assignedExerciseObjects: mAssignedExerciseObjects)
}


}

public class AssignedExerciseObject: NSObject, NSSecureCoding {


public static var supportsSecureCoding: Bool = true




public var mainExercise: String = ""
public var prepareTime: String = ""
public var exerciseTime: String = ""
public var highIntensityTime: String = ""
public var restTime: String = ""

public var highLowSplit: Bool = false
public var isCompleted: Bool = false
public var isSkipped: Bool = false

public var order: Double = 0




enum Key:String {
    case mainExercise = "mainExercise"
    case prepareTime = "prepareTime"
    case exerciseTime = "exerciseTime"
    case highIntensityTime = "highIntensityTime"
    case restTime = "restTime"
    case highLowSplit = "highLowSplit"
    case isCompleted = "isCompleted"
    case isSkipped = "isSkipped"
    case order = "order"
}

init(mainExercise: String, prepareTime: String, exerciseTime: String, highIntensityTime: String, restTime: String, highLowSplit: Bool, isCompleted: Bool, isSkipped: Bool, order: Double) {
    self.mainExercise = mainExercise
    self.prepareTime = prepareTime
    self.exerciseTime = exerciseTime
    self.highIntensityTime = highIntensityTime
    self.restTime = restTime
    self.highLowSplit = highLowSplit
    self.isCompleted = isCompleted
    self.isSkipped = isSkipped
    self.order = order
}

public override init() {
    super.init()
}

public func encode(with aCoder: NSCoder) {
    
    aCoder.encode(mainExercise, forKey: Key.mainExercise.rawValue)
    aCoder.encode(prepareTime, forKey: Key.prepareTime.rawValue)
    aCoder.encode(exerciseTime, forKey: Key.exerciseTime.rawValue)
    aCoder.encode(highIntensityTime, forKey: Key.highIntensityTime.rawValue)
    aCoder.encode(restTime, forKey: Key.restTime.rawValue)
    aCoder.encode(highLowSplit, forKey: Key.highLowSplit.rawValue)
    aCoder.encode(isCompleted, forKey: Key.isCompleted.rawValue)
    aCoder.encode(isSkipped, forKey: Key.isSkipped.rawValue)
    aCoder.encode(order, forKey: Key.order.rawValue)
}

public required convenience init?(coder aDecoder: NSCoder) {
    
    let mMainExercise = aDecoder.decodeObject(of: NSString.self, forKey: Key.mainExercise.rawValue)! as String
    let mPrepareTime = aDecoder.decodeObject(of: NSString.self,forKey: Key.prepareTime.rawValue)! as String
    let mExerciseTime = aDecoder.decodeObject(of: NSString.self,forKey: Key.exerciseTime.rawValue)! as String
    let mHighIntensityTime = aDecoder.decodeObject(of: NSString.self,forKey: Key.highIntensityTime.rawValue)! as String
    let mRestTime = aDecoder.decodeObject(of: NSString.self,forKey: Key.restTime.rawValue)! as String
    let mHighLowSplit = aDecoder.decodeBool(forKey: Key.highLowSplit.rawValue)
    let mIsCompleted = aDecoder.decodeBool(forKey: Key.isCompleted.rawValue)
    let mIsSkipped = aDecoder.decodeBool(forKey: Key.isSkipped.rawValue)
    let mOrder = aDecoder.decodeDouble(forKey: Key.order.rawValue)
 
    self.init(mainExercise: String(mMainExercise), prepareTime:
                String(mPrepareTime), exerciseTime: String(mExerciseTime), highIntensityTime: String(mHighIntensityTime), restTime: String(mRestTime), highLowSplit: Bool(mHighLowSplit), isCompleted: Bool(mIsCompleted), isSkipped: Bool(mIsSkipped), order: Double(mOrder))
    
    }
}

this is where it gives me the error

let mAssignedExerciseObjects = aDecoder.decodeObject(of: NSArray.self, forKey: Key.assignedExerciseObjects.rawValue) as! [AssignedExerciseObject]

I'm still fairly new to swift, but I cannot for the life of me work out why it is returning a nil value?

when the record is created, it all seems to work fine, but when I try to display the record in a table, I get the error

any help is greatly appreciated

regards

Jamie

  • 1
    Don’t use transformable attributes unless you have no choice. Here you have one, a second entity and to-many relationships. – vadian Jun 23 '21 at 08:59
  • Hi vadian thanks for the reply. I moved from a relationship to trabsformable, as there are potentially thousands of records that are stored in the transformable and syncing between devices took too long using relationships. My other option is to store all the values as json, but I would prefer to stick to transformables, as it would take quite a lot of time to rewrite for json – jamie hancock Jun 23 '21 at 20:40

1 Answers1

1

OK, I've fixed it

Adding my custom class fixed the issue

 let mAssignedExerciseObjects = aDecoder.decodeObject(of: [AssignedExerciseObject.self, NSArray.self], forKey: Key.assignedExerciseObjects.rawValue) as! [AssignedExerciseObject]