I have my UserDefaults like this
fileprivate enum userdefaultKeys: String {
userSearchHistory = "userSearchHistory",
}
extension UserDefaults {
static func getUserSearchHistory() -> SearchHistory? {
let data = self.standard.data(forKey: userdefaultKeys.userSearchHistory.rawValue)
return SearchHistory.decode(json: data)
}
static func setUserSearchHistory(userSearchHistory: SearchHistory?) {
guard let json: Any = userSearchHistory?.json else { return }
self.standard.set(json, forKey: userdefaultKeys.userSearchHistory.rawValue)
}
}
And I'm saving this data to the UserDefaults
struct SearchHistory: Codable {
let type: SearchHistoryEnum
let name: String
let corpNo: String
let storeNo: String
let long: Double
let lat: Double
}
enum SearchHistoryEnum: Codable {
case storeSearch
case jsonSearch
}
let historySearch = SearchHistory(type: SearchHistoryEnum.storeSearch, name: store?.storename ?? "", corpNo: store?.corpno ?? "", storeNo: store?.storeno ?? "", long: longtitude, lat: latitude)
UserDefaults.setUserSearchHistory(userSearchHistory: historySearch)
This is okay, but it saves only one instance of SearchHistory in the time. I would like to have max 5. When 6th instance comes, I would like to delete the most old one
First of all your enum doesn't compile, you probably mean
fileprivate enum UserdefaultKeys: String {
case userSearchHistory
}
It's not necessary to specify the raw value.
Second of all I highly recommend not to fight the framework and to conform to the UserDefaults pattern to overload the getter and setter. I don't know your special methods for decoding and encoding, this is a simple implementation with standard JSONDecoder and JSONEncoder
extension UserDefaults {
func searchHistory(forKey key: String = UserdefaultKeys.userSearchHistory.rawValue) -> SearchHistory? {
guard let data = data(forKey: key) else { return nil }
return try? JSONDecoder().decode(SearchHistory.self, from: data)
}
func searchHistory(forKey key: String = UserdefaultKeys.userSearchHistory.rawValue) -> [SearchHistory]? {
guard let data = data(forKey: key) else { return nil }
return try? JSONDecoder().decode([SearchHistory].self, from: data)
}
func set(_ value: SearchHistory, forKey key: String = UserdefaultKeys.userSearchHistory.rawValue) {
guard let data = try? JSONEncoder().encode(value) else { return }
set(data, forKey: key)
}
func set(_ value: [SearchHistory], forKey key: String = UserdefaultKeys.userSearchHistory.rawValue) {
guard let data = try? JSONEncoder().encode(value) else { return }
set(data, forKey: key)
}
}
The benefit is the syntax is always the same for a single item or for an array
let historySearch = SearchHistory(type: SearchHistoryEnum.storeSearch, name: store?.storename ?? "", corpNo: store?.corpno ?? "", storeNo: store?.storeno ?? "", long: longtitude, lat: latitude)
UserDefaults.standard.set(historySearch)
or
UserDefaults.standard.set([historySearch])
The code to delete the oldest put in the method to write the data.
Related
So I had this idea of creating an expiry for UserDefaults. This is the approach I was starting to take but I'm stuck.
struct TimedObject<T: Codable>: Codable {
let object: T
let expireDate: Date
}
and then:
extension UserDefaults {
func set<T: Codable>(_ value: T, forKey key: String, expireDate: Date) {
let timedObject = TimedObject<T>(object: value, expireDate: expireDate)
let encoder = JSONEncoder()
if let encoded = try? encoder.encode(timedObject) {
UserDefaults.standard.set(encoded, forKey: key)
}
override open class func value(forKey key: String) -> Any? {
guard let value = self.value(forKey: key) else {
return nil
}
if TimedObject<???>.self == type(of: value) { // This is where I'm stuck
...
}
}
So if I would name the type and not use generics I would easily solve this. But naturally I prefer to use generics. Can this be done?
I know OP is using a struct to wrap the stored value but I would still like to offer a different protocol based solution where any type that should be stored with an expiration date needs to conform to this protocol.
Here is the protocol for I am using
protocol TimedObject: Codable {
associatedtype Value: Codable
var value: Value { get }
var expirationDate: Date { get }
}
and the functions to store and retrieve from UserDefaults
extension UserDefaults {
func set<Timed: TimedObject>(_ value: Timed, forKey key: String) {
if let encoded = try? JSONEncoder().encode(value) {
self.set(encoded, forKey: key)
}
}
func value<Timed: TimedObject>(_ type: Timed.Type, forKey key: String) -> Timed.Value? {
guard let data = self.value(forKey: key) as? Data, let object = try? JSONDecoder().decode(Timed.self, from: data) else {
return nil
}
return object.expirationDate > .now ? object.value : nil
}
}
Finally an example
struct MyStruct: Codable {
let id: Int
let name: String
}
extension MyStruct: TimedObject {
typealias Value = Self
var value: MyStruct { self }
var expirationDate: Date {
.now.addingTimeInterval(24 * 60 * 60)
}
}
let my = MyStruct(id: 12, name: "abc")
UserDefaults.standard.set(my, forKey: "my")
let my2 = UserDefaults.standard.value(MyStruct.self, forKey: "my")
Since you're returning Any?, it is best to create another struct to point to TimedObject as you don't need the object property when returning Any?:
struct Expiry: Codable {
var expireDate: Date
}
struct TimedObject<T: Codable>: Timable {
let object: T
var expireDate: Date
}
override open class func value(forKey key: String) -> Any? {
guard let value = self.value(forKey: key) as? Data else {
return nil
}
if let timed = try? JSONDecoder().decode(Expiry.self, from: value) {
//do anything with timed
}
//make sure to return value
}
And here's a method to access TimedObject:
func timedObject<T: Codable>(forKey key: String) -> TimedObject<T>? {
guard let value = self.data(forKey: key) as? Data, let timed = try? JSONDecoder().decode(TimedObject<T>.self, from: value) else {
return nil
}
return value
}
If you make the value() method generic then you can reverse the process done in the set() method: retrieve the data and decode it as a TimedObject<T>.
However, I would choose a different name to avoid possible ambiguities with the exisiting value(forKey:) method. Also I see no reason why this should be a class method.
Note also that your generic set() method should call the non-generic version on the same instance.
extension UserDefaults {
func set<T: Codable>(_ value: T, forKey key: String, expireDate: Date) {
let timedObject = TimedObject(object: value, expireDate: expireDate)
let encoder = JSONEncoder()
if let encoded = try? encoder.encode(timedObject) {
set(encoded, forKey: key)
}
}
func expiringValue<T: Codable>(forKey key: String) -> T? {
guard let data = self.data(forKey: key) else {
return nil
}
let decoder = JSONDecoder()
guard let decoded = try? decoder.decode(TimedObject<T>.self, from: data) else {
return nil
}
// check expire date ...
return decoded.object
}
}
Example usage:
let val1 = UserDefaults.standard.expiringValue(forKey: "foo") as String?
let val2: String? = UserDefaults.standard.expiringValue(forKey: "bar")
In both cases, expiringValue(forKey:) is called with the inferred type.
Or in combination with optional binding:
if let val: String = UserDefaults.standard.expiringValue(forKey: "test") {
print(val)
}
Another option is to pass the desired type as an additional argument:
func value<T: Codable>(forKey key: String, as: T.Type) -> T? {
guard let data = self.data(forKey: key) else {
return nil
}
let decoder = JSONDecoder()
guard let decoded = try? decoder.decode(TimedObject<T>.self, from: data) else {
return nil
}
// check expire date ...
return decoded.object
}
which is then used as
let val = UserDefaults.standard.value(forKey: "foo", as: String.self)
I a codable serialization extension which I use to turn my Codable struct to dictionaries, the problem I am facing is strings. I get string value from my UITextField at at times this value could be empty and as a result an empty string is decoded. How can I return nil if the value is an empty string.
extension Encodable {
var requestDictionary: [String: Any]? {
let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .convertToSnakeCase
guard let data = try? encoder.encode(self) else { return nil }
return (try? JSONSerialization.jsonObject(with: data, options: .allowFragments)).flatMap { $0 as? [String: Any] }
}
}
if I have a Struct
let example = Exa(age: 10, name: "")
let dict = example.requestDictionary
print(dict)
I want it to just print ["age": 10] and return nil for the empty string
You can implement your own String encoding method extending KeyedEncodingContainer:
extension KeyedEncodingContainer {
mutating func encode(_ value: String, forKey key: K) throws {
guard !value.isEmpty else { return }
try encodeIfPresent(value, forKey: key)
}
}
Btw your request dictionary can be simplified as:
extension Encodable {
var dictionary: [String: Any]? {
let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .convertToSnakeCase
return try? JSONSerialization.jsonObject(with: encoder.encode(self)) as? [String: Any]
}
}
Playground testing:
struct Exa: Encodable {
let age: Int
let name: String
}
let example = Exa(age: 10, name: "")
let dict = example.dictionary!
print(dict) // "["age": 10]\n"
I'll just another approach using a property wrapper to mark which properties could be skipped.
#propertyWrapper
struct SkipEmpty {
var wrappedValue: String
}
extension SkipEmpty: Codable {
init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
self.wrappedValue = try container.decode(String.self)
}
func encode(to encoder: Encoder) throws {
// nothing to do here, see below
}
}
But to actually skip, you'd also need to create a overload for the KeyedEncodingContainer.encode method for the SkipEmpty type:
extension KeyedEncodingContainer {
mutating func encode(_ value: SkipEmpty, forKey key: K) throws {
if !value.wrappedValue.isEmpty {
try encode(value.wrappedValue, forKey: key) // encode the value here
}
}
}
You could possibly try to make it more generic, e.g. SkipEmpty<T: Codable> and provide another argument for the value to skip or a predicate, etc...
The usage is:
struct Exa: Encodable {
var age: Int
#SkipEmpty var name: String
}
I'm using this library which has created non-empty collections like arrays, dictionaries and strings. https://github.com/pointfreeco/swift-nonempty
When I decode to the non-empty array I get the following error
Swift.DecodingError.typeMismatch(Swift.Dictionary, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "poiList", intValue: nil)], debugDescription: "Expected to decode Dictionary but found an array instead.", underlyingError: nil))
This is my structure
struct LocationCarModel: Codable {
// MARK: - Properties
var poiList: NonEmptyArray<PointOfInterest>
// MARK: - PointOfInterest
struct PointOfInterest: Codable {
var id: Int
var coordinate: Position
var fleetType: String
let numberPlate = "HCD837EC"
let model: String = "Tesla S"
let fuel: Double = 0.9
}
}
This is the response I'm getting https://fake-poi-api.mytaxi.com/?p2Lat=53.394655&p1Lon=9.757589&p1Lat=53.694865&p2Lon=10.099891
and this how I'm decoding it.
public extension Decodable {
static func parse(from item: Any?, strategy: JSONDecoder.KeyDecodingStrategy = .useDefaultKeys) -> Self? {
guard let data = self.data(from: item) else {
return nil
}
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = strategy
do {
let result = try decoder.decode(Self.self, from: data)
return result
} catch {
debugPrint(error)
return nil
}
}
private static func data(from item: Any?) -> Data? {
switch item {
case let data as Data:
return data
case let string as String:
return string.data(using: .utf8)
case .some(let item):
return try? JSONSerialization.data(withJSONObject: item, options: [])
case nil:
return nil
}
}
}
and the line to decode using the above function is
let model = LocationCarModel.parse(from: data)
Changing poiList to the standard swift array then no error occurs.
Any ideas how I can solve this issue? Any help would be appreciated. Thank you in advance.
You need to have your own init(from:) for the top struct since JSONDecoder doesn't understand NonEmpty and how to initialise it. Apart from the init I also added coding keys and a new error
enum DecodeError: Error {
case arrayIsEmptyError
}
struct LocationCarModel: Codable {
var poiList: NonEmpty<[PointOfInterest]>
enum CodingKeys: String, CodingKey {
case poiList
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let array = try container.decode([PointOfInterest].self, forKey: .poiList)
guard let first = array.first else {
throw DecodeError.arrayIsEmptyError
}
poiList = NonEmptyArray(first, array)
}
//...
}
You can try
struct Root: Codable {
let poiList: [PoiList]
}
// MARK: - PoiList
struct PoiList: Codable {
let id: Int
let coordinate: Coordinate
let fleetType: String
let heading: Double
}
// MARK: - Coordinate
struct Coordinate: Codable {
let latitude, longitude: Double
}
let res = try? JSONDecoder().decode(Root.self,from:data)
print(res)
I have a simple object which conforms to the NSCoding protocol.
import Foundation
class JobCategory: NSObject, NSCoding {
var id: Int
var name: String
var URLString: String
init(id: Int, name: String, URLString: String) {
self.id = id
self.name = name
self.URLString = URLString
}
// MARK: - NSCoding
required init(coder aDecoder: NSCoder) {
id = aDecoder.decodeObject(forKey: "id") as? Int ?? aDecoder.decodeInteger(forKey: "id")
name = aDecoder.decodeObject(forKey: "name") as! String
URLString = aDecoder.decodeObject(forKey: "URLString") as! String
}
func encode(with aCoder: NSCoder) {
aCoder.encode(id, forKey: "id")
aCoder.encode(name, forKey: "name")
aCoder.encode(URLString, forKey: "URLString")
}
}
I'm trying to save an instance of it in UserDefaults but it keeps failing with the following error.
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Attempt to insert non-property list object for key jobCategory'
This is the code where I'm saving in UserDefaults.
enum UserDefaultsKeys: String {
case jobCategory
}
class ViewController: UIViewController {
#IBAction func didTapSaveButton(_ sender: UIButton) {
let category = JobCategory(id: 1, name: "Test Category", URLString: "http://www.example-job.com")
let userDefaults = UserDefaults.standard
userDefaults.set(category, forKey: UserDefaultsKeys.jobCategory.rawValue)
userDefaults.synchronize()
}
}
I replaced the enum value to key with a normal string but the same error still occurs. Any idea what's causing this?
You need to create Data instance from your JobCategory model using JSONEncoder and store that Data instance in UserDefaults and later decode using JSONDecoder.
struct JobCategory: Codable {
let id: Int
let name: String
}
// To store in UserDefaults
if let encoded = try? JSONEncoder().encode(category) {
UserDefaults.standard.set(encoded, forKey: UserDefaultsKeys.jobCategory.rawValue)
}
// Retrieve from UserDefaults
if let data = UserDefaults.standard.object(forKey: UserDefaultsKeys.jobCategory.rawValue) as? Data,
let category = try? JSONDecoder().decode(JobCategory.self, from: data) {
print(category.name)
}
Old Answer
You need to create Data instance from your JobCategory instance using archivedData(withRootObject:) and store that Data instance in UserDefaults and later unarchive using unarchiveTopLevelObjectWithData(_:), So try like this.
For Storing data in UserDefaults
let category = JobCategory(id: 1, name: "Test Category", URLString: "http://www.example-job.com")
let encodedData = NSKeyedArchiver.archivedData(withRootObject: category, requiringSecureCoding: false)
let userDefaults = UserDefaults.standard
userDefaults.set(encodedData, forKey: UserDefaultsKeys.jobCategory.rawValue)
For retrieving data from UserDefaults
let decoded = UserDefaults.standard.object(forKey: UserDefaultsKeys.jobCategory.rawValue) as! Data
let decodedTeams = NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(decoded) as! JobCategory
print(decodedTeams.name)
Update Swift 4, Xcode 10
I have written a struct around it for easy access.
//set, get & remove User own profile in cache
struct UserProfileCache {
static let key = "userProfileCache"
static func save(_ value: Profile!) {
UserDefaults.standard.set(try? PropertyListEncoder().encode(value), forKey: key)
}
static func get() -> Profile! {
var userData: Profile!
if let data = UserDefaults.standard.value(forKey: key) as? Data {
userData = try? PropertyListDecoder().decode(Profile.self, from: data)
return userData!
} else {
return userData
}
}
static func remove() {
UserDefaults.standard.removeObject(forKey: key)
}
}
Profile is a Json encoded object.
struct Profile: Codable {
let id: Int!
let firstName: String
let dob: String!
}
Usage:
//save details in user defaults...
UserProfileCache.save(profileDetails)
Hope that helps!!!
Thanks
Swift save Codable object to UserDefault with #propertyWrapper
#propertyWrapper
struct UserDefault<T: Codable> {
let key: String
let defaultValue: T
init(_ key: String, defaultValue: T) {
self.key = key
self.defaultValue = defaultValue
}
var wrappedValue: T {
get {
if let data = UserDefaults.standard.object(forKey: key) as? Data,
let user = try? JSONDecoder().decode(T.self, from: data) {
return user
}
return defaultValue
}
set {
if let encoded = try? JSONEncoder().encode(newValue) {
UserDefaults.standard.set(encoded, forKey: key)
}
}
}
}
enum GlobalSettings {
#UserDefault("user", defaultValue: User(name:"",pass:"")) static var user: User
}
Example User model confirm Codable
struct User:Codable {
let name:String
let pass:String
}
How to use it
//Set value
GlobalSettings.user = User(name: "Ahmed", pass: "Ahmed")
//GetValue
print(GlobalSettings.user)
Save dictionary Into userdefault
let data = NSKeyedArchiver.archivedData(withRootObject: DictionaryData)
UserDefaults.standard.set(data, forKey: kUserData)
Retrieving the dictionary
let outData = UserDefaults.standard.data(forKey: kUserData)
let dict = NSKeyedUnarchiver.unarchiveObject(with: outData!) as! NSDictionary
Based on Harjot Singh answer. I've used like this:
struct AppData {
static var myObject: MyObject? {
get {
if UserDefaults.standard.object(forKey: "UserLocationKey") != nil {
if let data = UserDefaults.standard.value(forKey: "UserLocationKey") as? Data {
let myObject = try? PropertyListDecoder().decode(MyObject.self, from: data)
return myObject!
}
}
return nil
}
set {
UserDefaults.standard.set(try? PropertyListEncoder().encode(newValue), forKey: "UserLocationKey")
}
}
}
Here's a UserDefaults extension to set and get a Codable object, and keep it human-readable in the plist (User Defaults) if you open it as a plain text file:
extension Encodable {
var asDictionary: [String: Any]? {
guard let data = try? JSONEncoder().encode(self) else { return nil }
return try? JSONSerialization.jsonObject(with: data) as? [String : Any]
}
}
extension Decodable {
init?(dictionary: [String: Any]) {
guard let data = try? JSONSerialization.data(withJSONObject: dictionary) else { return nil }
guard let object = try? JSONDecoder().decode(Self.self, from: data) else { return nil }
self = object
}
}
extension UserDefaults {
func setEncodableAsDictionary<T: Encodable>(_ encodable: T, for key: String) {
self.set(encodable.asDictionary, forKey: key)
}
func getDecodableFromDictionary<T: Decodable>(for key: String) -> T? {
guard let dictionary = self.dictionary(forKey: key) else {
return nil
}
return T(dictionary: dictionary)
}
}
If you want to also support array (of codables) to and from plist array, add the following to the extension:
extension UserDefaults {
func setEncodablesAsArrayOfDictionaries<T: Encodable>(_ encodables: Array<T>, for key: String) {
let arrayOfDictionaries = encodables.map({ $0.asDictionary })
self.set(arrayOfDictionaries, forKey: key)
}
func getDecodablesFromArrayOfDictionaries<T: Decodable>(for key: String) -> [T]? {
guard let arrayOfDictionaries = self.array(forKey: key) as? [[String: Any]] else {
return nil
}
return arrayOfDictionaries.compactMap({ T(dictionary: $0) })
}
}
If you don't care about plist being human-readable, it can be simply saved as Data (will look like random string if opened as plain text):
extension UserDefaults {
func setEncodable<T: Encodable>(_ encodable: T, for key: String) throws {
let data = try PropertyListEncoder().encode(encodable)
self.set(data, forKey: key)
}
func getDecodable<T: Decodable>(for key: String) -> T? {
guard
self.object(forKey: key) != nil,
let data = self.value(forKey: key) as? Data
else {
return nil
}
let obj = try? PropertyListDecoder().decode(T.self, from: data)
return obj
}
}
(With this second approach, you don't need the Encodable and Decodable extensions from the top)
Well, investigated several similar topics here, done everything as suggested, but my computed property "previousUserData" returns me nil, when trying to cast the decoded object to my type. What's wrong?
#objc class PreviousUserData: NSObject, NSCoding {
var name: String
var phone: String
var email: String
func encode(with aCoder: NSCoder) {
aCoder.encode(name, forKey: "name")
aCoder.encode(phone, forKey: "phone")
aCoder.encode(email, forKey: "email")
}
required convenience init?(coder aDecoder: NSCoder) {
guard
let name = aDecoder.decodeObject(forKey: "name") as? String,
let phone = aDecoder.decodeObject(forKey: "phone") as? String,
let email = aDecoder.decodeObject(forKey: "email") as? String
else {
return nil
}
self.init(name: name, phone: phone, email: email)
}
init(name: String, phone: String, email: String) {
self.name = name
self.phone = phone
self.email = email
}
}
unarchived returns me nil, but data for key "userdata" is exists
var previousUserData: PreviousUserData? {
get {
if let object = UserDefaults.standard.object(forKey: "userdata") as? Data {
let unarchived = NSKeyedUnarchiver.unarchiveObject(with: object) as? PreviousUserData
return unarchived
}
return nil
}
set {
let encodedData: Data = NSKeyedArchiver.archivedData(withRootObject: previousUserData as Any)
UserDefaults.standard.setValue(encodedData, forKey: "userdata")
}
}
Actually you can't get valid data because the setter is wrong. You have to save newValue rather than previousUserData.
This is an slightly optimized version
var previousUserData: PreviousUserData? {
get {
guard let data = UserDefaults.standard.data(forKey: "userdata") else { return nil }
return NSKeyedUnarchiver.unarchiveObject(with: data) as? PreviousUserData
}
set {
guard let newValue = newValue else { return }
let encodedData = NSKeyedArchiver.archivedData(withRootObject: newValue)
UserDefaults.standard.set(encodedData, forKey: "userdata")
}
}
NSCoding is pretty heavy. In this case I'd recommend to use Codable to serialize the data as JSON or Property List. It gets rid of #objc, class and NSObject and reduces the entire code to
struct PreviousUserData : Codable {
var name: String
var phone: String
var email: String
}
var previousUserData: PreviousUserData? {
get {
guard let data = UserDefaults.standard.data(forKey: "userdata") else { return nil }
return try? JSONDecoder().decode(PreviousUserData.self, from: data)
}
set {
guard let newValue = newValue, let encodedData = try? JSONEncoder().encode(newValue) else { return }
UserDefaults.standard.set(encodedData, forKey: "userdata")
}
}