arraysswiftdata-structurescore-datastruct
How to delete and update structure type array in Core Data iOS Swift?
How to delete and update structure type array in Core Data iOS Sswift? I am saving to core data like this. I need to delete and update selected cell containing values
let projectsInfo = NSEntityDescription.insertNewObject(forEntityName:"ItemsInfo", into: delegate.persistentContainer.viewContext) as! ItemsInfo
let auditArray:[String:[lendingData]] = ["allcreditData":SaveWitnessData.shared.LendingDataArray]
let jsonData = try! JSONEncoder().encode(auditArray) projectsInfo.values = jsonData
delegate.saveContext()
And my struct is like
struct lendingData : Codable {
let userName : String
let amount : String
let date : String
let type : String
var witnessDetails : [witnessData]
}
Solution
Option 1.
Using a class and NSSecureCoding is the best way of doing this. The most flexible.
///To See the whole thing in action you have to follow a few steps
///Step 1. Create an new SwiftUI project with CoreData
///Step 2. Copy all the code in Option 1 into a `.swift` file
///Step 3. Go to the `Persistence.swift` file
/// Place these 2 lines
/// `WitnessDataTransformer.register()`
/// `LendingDataTransformer.register()`
/// Just under `container = NSPersistentCloudKitContainer(name: "YourAppName")
///Step 4. Go to the CoreData model
/// Select the `Item` Entity
/// Add a `lendingData` attribute of type `Transformable`
/// Update the `Transformer` and `Custom Class` in the `Data Model Inspector` as shown
///Step 5. You should see the View on Canvas in this point
Photo for Step 4
Code
import SwiftUI
//struct and class should start with an uppercase
//You need secureCoding not codable
//You have to change to class because NSSecurecoding is not available for a struct -https://developer.apple.com/documentation/foundation/nssecurecoding
public class LendingData : NSObject, Identifiable, ObservableObject{
public let id: String
@Published var userName : String
@Published var amount : String
@Published var date : String
@Published var type : String
//WitnessData needs to conform to secure coding as well
@Published var witnessDetails : [WitnessData]
static func sample() -> LendingData {
LendingData(id: UUID().uuidString, userName: "sample name", amount: "10.00", date: "\(Date())", type: "sample type", witnessDetails: [WitnessData.sample(), WitnessData.sample()])
}
static func blank() -> LendingData {
LendingData(id: UUID().uuidString, userName: "", amount: "", date: "", type: "", witnessDetails: [])
}
public enum CodingKeys: String, CodingKey {
case id
case userName
case amount
case date
case type
case witnessDetails
}
public init(id: String, userName : String, amount : String, date : String, type : String, witnessDetails : [WitnessData]) {
self.id = id
self.userName = userName
self.amount = amount
self.date = date
self.type = type
self.witnessDetails = witnessDetails
}
public required init?(coder: NSCoder) {
id = coder.decodeObject(forKey: CodingKeys.id.rawValue) as! String
userName = coder.decodeObject(forKey: CodingKeys.userName.rawValue) as! String
amount = coder.decodeObject(forKey: CodingKeys.amount.rawValue) as! String
date = coder.decodeObject(forKey: CodingKeys.date.rawValue) as! String
type = coder.decodeObject(forKey: CodingKeys.type.rawValue) as! String
witnessDetails = coder.decodeArrayOfObjects(ofClass: WitnessData.self, forKey: CodingKeys.witnessDetails.rawValue) ?? []
}
}
extension LendingData: NSSecureCoding{
public static var supportsSecureCoding: Bool{
return true
}
public func encode(with coder: NSCoder) {
coder.encode(id, forKey: CodingKeys.id.rawValue)
coder.encode(userName, forKey: CodingKeys.userName.rawValue)
coder.encode(amount, forKey: CodingKeys.amount.rawValue)
coder.encode(date, forKey: CodingKeys.date.rawValue)
coder.encode(type, forKey: CodingKeys.type.rawValue)
coder.encode(witnessDetails, forKey: CodingKeys.witnessDetails.rawValue)
}
}
///MUST CALL LendingDataTransformer.register() right after creating the Persistent Container before setup and loading store
@objc(LendingDataTransformer)
public final class LendingDataTransformer: NSSecureUnarchiveFromDataTransformer {
public static let name = NSValueTransformerName(rawValue: String(describing: LendingDataTransformer.self))
public override static var allowedTopLevelClasses: [AnyClass] {
return [LendingData.self, NSString.self, NSArray.self, WitnessData.self]
}
//Register before CoreData setup starts
@objc dynamic
public static func register() {
let transformer = LendingDataTransformer()
ValueTransformer.setValueTransformer(transformer, forName: name)
}
}
//You have to change to class because NSSecurecoding is not available for a struct -https://developer.apple.com/documentation/foundation/nssecurecoding
public class WitnessData: NSObject, Identifiable, ObservableObject{
public let id: String
//This is just a sample since you did not provide the struct
//Add your variables to
// the class,
// the CodingKeys,
// init?(coder: NSCoder),
// encode(with coder: NSCoder), and
// init(id: String, name : String).
// Just follow the pattern.
@Published var name: String
static func sample() -> WitnessData{
WitnessData(id: UUID().uuidString, name: UUID().uuidString)
}
static func blank() -> WitnessData{
WitnessData(id: UUID().uuidString, name: "")
}
public enum CodingKeys: String, CodingKey {
case id
case name
}
public init(id: String, name : String) {
self.id = id
self.name = name
}
public required init?(coder: NSCoder) {
id = coder.decodeObject(forKey: CodingKeys.id.rawValue) as? String ?? ""
name = coder.decodeObject(forKey: CodingKeys.name.rawValue) as? String ?? ""
}
}
extension WitnessData: NSSecureCoding{
public static var supportsSecureCoding: Bool{
return true
}
public func encode(with coder: NSCoder) {
coder.encode(id, forKey: CodingKeys.id.rawValue)
coder.encode(name, forKey: CodingKeys.name.rawValue)
}
}
///MUST CALL WitnessDataTransformer.register() right after creating the Persistent Container before setup and loading store
@objc(WitnessDataTransformer)
public final class WitnessDataTransformer: NSSecureUnarchiveFromDataTransformer {
public static let name = NSValueTransformerName(rawValue: String(describing: WitnessDataTransformer.self))
public override static var allowedTopLevelClasses: [AnyClass] {
return [WitnessData.self, NSString.self, NSArray.self]
}
//Register before CoreData setup starts
@objc dynamic
public static func register() {
let transformer = WitnessDataTransformer()
ValueTransformer.setValueTransformer(transformer, forName: name)
}
}
The below SwiftUI code works for both option 1 or option 2
///This is just a sample View
struct LendingDataView: View {
//You will need the original ObservableObject if you want to be able to show changes
//SwiftUI depends on being told that there are chagnes so it can reload Views
@ObservedObject var item: Item
var body: some View {
if item.lendingData != nil{
List{
TextField("username",text: $item.lendingData.bound.userName)
TextField("amount",text: $item.lendingData.bound.amount)
TextField("date",text: $item.lendingData.bound.date)
TextField("type",text: $item.lendingData.bound.type)
Section(content: {
ForEach($item.lendingData.bound.witnessDetails, content: { $witness in
HStack{
TextField("name",text: $witness.name)
Spacer()
//For deleting by object
Image(systemName: "trash")
.foregroundColor(.red)
.onTapGesture {
let idx = item.lendingData!.witnessDetails.firstIndex(where: {
$0.id == witness.id
})
if idx != nil{
item.lendingData!.witnessDetails.remove(at: idx!)
}
//Because you are so far down the line you have to tell the ObservableObject there is a change
//If you dont you won't see the new items until something happens to trigger a refresh
//item.objectWillChange.send()
item.objectWillChange.send()
}
}
})
//For deleting by index
.onDelete(perform: { indexSet in
for idx in indexSet{
item.lendingData!.witnessDetails.remove(at: idx)
}
})
}, header: {
HStack{
Text("Witness Data")
Button(action: {
item.lendingData!.witnessDetails.append(WitnessData.blank())
//Because you are so far down the line you have to tell the ObservableObject there is a change
//If you dont you won't see the new items until something happens to trigger a refresh
item.objectWillChange.send()
}, label: {
Image(systemName: "plus")
})
}
})
}
}else{
VStack{
Text("no lending data")
Button(action: {
item.lendingData = LendingData.blank()
}, label: {
Image(systemName: "plus")
})
}
}
}
}
//Standard Preview
struct LendingDataView_Previews: PreviewProvider {
//Use the preview container
static let context = PersistenceController.preview.container.viewContext
static var sampleItem = Item(context: context)
static var previews: some View {
LendingDataView(item: sampleItem)
}
}
extension Optional where Wrapped == LendingData {
var _bound: LendingData? {
get {
return self
}
set {
self = newValue
}
}
var bound: LendingData {
get {
return _bound ?? LendingData.blank()
}
set {
_bound = newValue
}
}
}
Like I said at the start class is the safest way but you can use the struct.
Option 2
Just add an an attribute named lendingDataJSON of Type String? INSTEAD of the lendingData of type Transformable
struct LendingData : Codable, Identifiable{
let id: String
var userName : String
var amount : String
var date : String
var type : String
var witnessDetails : [WitnessData]
static func sample() -> LendingData {
LendingData(id: UUID().uuidString, userName: "sample name", amount: "10.00", date: "\(Date())", type: "sample type", witnessDetails: [WitnessData.sample(), WitnessData.sample()])
}
static func blank() -> LendingData {
LendingData(id: UUID().uuidString, userName: "", amount: "", date: "", type: "", witnessDetails: [])
}
}
struct WitnessData: Codable, Identifiable{
let id: String
var name: String
static func sample() -> WitnessData{
WitnessData( id: UUID().uuidString, name: UUID().uuidString)
}
static func blank() -> WitnessData{
WitnessData( id: UUID().uuidString, name: "")
}
}
//The App's CoreData Model will need an attibute
// named lendingDataJSON of Type String
extension Item{
//This computed property should be the only way that the app alters the LendingData
//If you use the lendingDataJSON directly you can corrupt all of it
var lendingData: LendingData?{
get{
let decoder = JSONDecoder()
if let obj = try? decoder.decode(LendingData.self, from: self.lendingDataJSON?.data(using: .utf8) ?? Data()) {
return obj
}else{
return nil
}
}
set{
let encoder = JSONEncoder()
encoder.outputFormatting = .prettyPrinted
if let encoded = try? encoder.encode(newValue) {
self.lendingDataJSON = String(data: encoded, encoding: .utf8) ?? ""
}
}
}
}
All the View code will work the same with the class option or with the struct option
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