如何在NSUserDefaults中使用（多种类型）保存数组

Question

This is pretty simple but can't seem to find the correct information to solve saving an array like this in User Defaults.

It says it's not a property that NSUser Defaults Excepts.

Code:

    var notificationList: [(type: String,imageName: String, text: String, date: String, seen: Bool)] = [(type: "Default",imageName: "ClearPartioned", text: "", date: "", seen: true)]


    if (UserDefaults.standard.object(forKey: "notificationList")) == nil { // first time launching

        print("making notification list")

        UserDefaults.standard.set(notificationList, forKey: "notificationList")
        UserDefaults.standard.synchronize()

        print("\(notificationList)")

    } else {

        print("getting saved array")

        notificationList = (UserDefaults.standard.object(forKey: "notificationList") as! [(type: String, imageName: String, text: String, date: String, seen: Bool)])

        print("\(notificationList)")
    }

Update:

This is closer but gives error found in this question here . These are the closet answers I have been able to find and there either out dated or crash the system.

Code:

    if (UserDefaults.standard.object(forKey: "notificationList")) == nil { // first time launching

        print("making notification list")

        let encodedData = NSKeyedArchiver.archivedData(withRootObject: notificationList)
        UserDefaults.standard.set(encodedData, forKey: "notificationList")
        UserDefaults.standard.synchronize()

    } else {

        print("getting saved array")

        notificationList = (UserDefaults.standard.object(forKey: "notificationList") as! [(type: String, imageName: String, text: String, date: String, seen: Bool)])

        print("\(notificationList)")
    }

Update 2: This is best answer implementation From Dhiru

Code:

  if (UserDefaults.standard.object(forKey: "notificationList")) == nil { // first time launching
        print("making notification list")

        let notificationData = NSKeyedArchiver.archivedData(withRootObject: notificationList)
        UserDefaults.standard.set(notificationData, forKey: "notificationList")
        UserDefaults.standard.synchronize()

    } else {

        print("getting saved array")

        let decodedData  = UserDefaults.standard.object(forKey: "notificationList") as! Data
        let notificationList = NSKeyedUnarchiver.unarchiveObject(with: decodedData) as AnyObject

        print("\(notificationList)")
    }

Its giving me an error that crashes system

   *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_SwiftValue encodeWithCoder:]: unrecognized selector sent to instance 0x1c011f380'
   libc++abi.dylib: terminating with uncaught exception of type NSException

Im sure this code would fix it but this is horribly implemented with multiple errors below because I have no clue how to use this code.

Code:

   func (coder aDecoder: NSCoder) {
        if let notificationList = aDecoder.decodeObjectForKey("notificationList") {
            self.notificationList = notificationList
        }
    }

    func encodeWithCoder(aCoder: NSCoder) {
        if let notificationList = notificationList {
            aCoder.encodeObject(notificationList, forKey: "notificationList")
        }
    }

Answer 1

You have to store your Object in form of Data Convert into data using NSKeyedArchiver.archivedData(withRootObject:)

Convert back to Object using NSKeyedUnarchiver.unarchiveObject(with:)

Saving Data for UserDefaults

let notificationData = NSKeyedArchiver.archivedData(withRootObject: notificationList)
UserDefaults.standard.set(notificationData, forKey: "notificationList")

Retrive Data from User UserDefaults

let decodedData  = UserDefaults.standard.object(forKey: "notificationList") as! Data
let notificationList = NSKeyedUnarchiver.unarchiveObject(with: decodedData) as! AnyObject

Answer 2

This is how I actually save a Custom Object created in the app in Swift 4 .

First, we create 3 protocols for our purpose of saving the custom object in UserDefaults . The logic behind is to convert the Custom Object into a normalized Dictionary/Array form.

This can be applied to any kind of Object which you have created.

The 3 protocols are:

1. Decoder (Used to decode the dictionary into custom object)
2. Encoder (Used to encode the custom object into dictionary)
3. UserDefaultsProtocol (Used to save, delete, update & retrieve the custom object from UserDefault )

Decoder Protocol

protocol Decoder {
    associatedtype T
    static func decode(dictionary: [String: Any]) -> T
}

Encoder Protocol

protocol Encoder {
    func encode() -> [String: Any]
}

UserDefaultsProtocol

protocol UserDefaultsDelegate: class {
    associatedtype T
    func saveToUserDefaults()
    static func removeFromUserDefaults()
    static func retrieveFromUserDefaults() -> T?
}

As per your question, NotificationList Object would look like this

class NotificationList {
    var type: String = ""
    var imageName: String = ""
    var text: String = ""
    var date: String = ""
    var seen: Bool = false
}

Now, you need to confirm all the 3 mentioned protocols to NotificationList . (Swift Best Practice: Use of Extensions & Protocols)

class NotificationList {
    private struct Constants {
        static let RootKey = "notification_list"
        static let TypeKey = "type"
        static let ImageNameKey = "image_name"
        static let TextKey = "text"
        static let DateKey = "date"
        static let SeenKey = "seen"
    }

    var type: String = ""
    var imageName: String = ""
    var text: String = ""
    var date: String = ""
    var seen: Bool = false

    typealias T = NotificationList
}

extension NotificationList: Encoder {
    func encode() -> [String : Any] {
        return [
            Constants.TypeKey: type,
            Constants.ImageNameKey: imageName,
            Constants.TextKey: text,
            Constants.DateKey: date,
            Constants.SeenKey: seen
        ]
    }
}

extension NotificationList: Decoder {
    static func decode(dictionary: [String: Any]) -> NotificationList {
        let type = dictionary[Constants.TypeKey] as! String
        let imageName = dictionary[Constants.ImageNameKey] as! String
        let text = dictionary[Constants.TextKey] as! String
        let date = dictionary[Constants.DateKey] as! String
        let seen = dictionary[Constants.SeenKey] as! Bool

        let notificationList = NotificationList()
        notificationList.type = type
        notificationList.imageName = imageName
        notificationList.text = text
        notificationList.date = date
        notificationList.seen = seen
        return notificationList
    }
}

extension NotificationList: UserDefaultsDelegate {

    func saveToUserDefaults() {
        UserDefaults.standard.setValue(encode(), forKey: Constants.RootKey)
    }

    static func retrieveFromUserDefaults() -> NotificationList? {
        guard let encodedNotificationList = UserDefaults.standard.dictionary(forKey: Constants.RootKey) else {
            return nil
        }
        return NotificationList.decode(dictionary: encodedNotificationList)
    }

    static func removeFromUserDefaults() {
        UserDefaults.standard.removeObject(forKey: Constants.RootKey)
    }
}

How to save NotificationList to UserDefaults?

var notificationList = NotificationList()
notificationList.type = "Default"
notificationList.imageName = "ClearPartioned"
notificationList.text = ""
notificationList.date = ""
notificationList.seen = true

Save to UserDefaults

notificationList.saveToUserDefaults()

Retrieve from UserDefaults

if let notificationList = NotificationList.retrieveFromUserDefaults() {
      // You will get the instance of notification list saved in UserDefaults
}

HOW TO SAVE ARRAY OF NOTIFICATION LIST?

Say notificationLists contains the array of notificationList objects.

var notificationListsArray = [[String: Any]]()

notificationLists.forEach {
     notificationListsArray.append($0.encode())
}

Save that array of dictionary to UserDefaults

UserDefaults.standard.setValue(notificationListsArray, forValue: "notificationLists")