When creating a class, what is the difference between these 2 implementations of creating a custom class in regards to security. They both work the exact same as far as I've used them, but have heard using private variables is the proper way to create classes
class Person {
var name:String
var age:Int
init(name: String, age: Int){
self.name = name
self.age = age
}
}
and
class Person {
private var _name: String
private var _age: Int
var name: String {
set {
self._name = newValue
} get {
return _name
}
}
var age: Int {
set {
self._age = newValue
} get {
return _age
}
}
init(name: String, age: Int){
self._name = name
self._age = age
}
}
private is definitely recommended to use but only in cases when you want that kind of privacy for your properties.
Your second code is not ensuring any kind of privacy. That's just adding more code unnecessarily.
There can be a scenario where you want to keep the write access private to the type (class/struct) and allow read access outside the type. For that you can use private(set) access modifier with your properties, i.e.
class Person {
private(set) var name: String
private(set) var age: Int
init(name: String, age: Int){
self.name = name
self.age = age
}
}
Related
I have a phone number model which looks like this:
import UIKit
import Foundation
struct PhoneValidation : OptionSet {
let rawValue: Int
static let phoneInValid = PhoneValidation(rawValue: 1 << 0)
static let phoneValid = PhoneValidation(rawValue: 1 << 1)
static let smsValidationAttempted = PhoneValidation(rawValue: 1 << 2)
static let smsValidationFailed = PhoneValidation(rawValue: 1 << 3)
static let smsValidationSuccessful = PhoneValidation(rawValue: 1 << 4) // OTP is successfully validated in backend. The field should be non-editable in this duration
static let smsValidationOTPTriggered = PhoneValidation(rawValue: 1 << 5) // OTP validation triggered. The field should be non-editable in this duration
}
class PhonesViewModel: NSCopying {
public var phoneType: PhoneNumberType = PhoneNumberType.mobile
public var phone: String?
public var code: String?
public var countryCode: String?
public var isValid : PhoneValidation?
func copy(with zone: NSZone? = nil) -> Any {
let copy = PhonesViewModel()
copy.phoneType = phoneType
copy.phone = phone
copy.code = code
copy.countryCode = countryCode
copy.isValid = isValid
return copy
}
}
As you can see above the phone model can transition between different states. The SMS validation is available for few countries and for few it is not applicable. So, I plan on setting smsValidationOTPTriggered state when SMS validation is applicable for a country and while the validation is in progress.
What I need here is, while the states smsValidationOTPTriggered or smsValidationSuccessful are set I would not want any module of the application to modify the values(phoneType, phone, code, countryCode) of the model. In other words, I would like the model to switch to a read-only mode while these 2 states are set in model and would like the module to be informed with an error or exception when a modification is attempted.
Is there a best practice already available for what I am trying to achieve here? I have searched before raising this question but did not find any. How can I achieve this?
Thanks,
Raj Pawan Gumdal
How about something like this, I think its better to use property wrappers for your case! The below is not an exact solution but can modify/change to accommodate your need
import UIKit
enum PhoneNumberType {
case mobile
}
enum PhoneValidation {
case phoneInValid
case phoneValid
case smsValidationAttempted
case smsValidationFailed
case smsValidationSuccessful
case smsValidationOTPTriggered
}
struct PhonesViewModel {
public var phoneType: PhoneNumberType = PhoneNumberType.mobile
public var phone: String?
public var code: String?
public var countryCode: String?
public var phoneValidation : PhoneValidation?
func validate(value: [PhoneValidation]) -> Bool {
//add proper check here
return false
}
}
#propertyWrapper
struct Wrapper {
private(set) var value: PhonesViewModel? = nil
var validators: [PhoneValidation] = []
var wrappedValue: PhonesViewModel? {
get { value }
set {
if let model = newValue, model.validate(value: validators) {
value = newValue
print("Value assigned")
} else {
print("Value not assigned")
}
}
}
}
struct SomeOtherClass {
#Wrapper(validators: [PhoneValidation.phoneInValid])
var model: PhonesViewModel?
}
var a = SomeOtherClass()
a.model = PhonesViewModel()
a.model = PhonesViewModel()
You can use a technique with the name "popsicle immutability". An object is initially mutable, but can be "frozen". Modifications for frozen objects are forbidden. In your case PhonesViewModel become frozen when isValid property have value smsValidationOTPTriggered or smsValidationSuccessful.
Let's add Freezable protocol for requirements to objects that can become immutable and conforming for PhonesViewModel:
protocol Freezable: class {
var isFrozen: Bool { get }
}
extension PhonesViewModel: Freezable {
var isFrozen: Bool {
isValid == .smsValidationOTPTriggered || isValid == .smsValidationSuccessful
}
}
Now we must add validation for isFrozen value when a property is assigned. It can be added in property observers like:
...
public var phone: String? {
didSet {
validate()
}
}
...
private func validate() {
assert(!isFrozen)
}
Or using property wrapper:
#propertyWrapper
struct Guarded<Value> {
private var value: Value
init(wrappedValue: Value) {
value = wrappedValue
}
#available(*, unavailable)
var wrappedValue: Value {
get { fatalError("only works on instance properties of classes that conforms to Freezable protocol") }
set { fatalError("only works on instance properties of classes that conforms to Freezable protocol") }
}
static subscript<EnclosingSelf: Freezable>(
_enclosingInstance object: EnclosingSelf,
wrapped wrappedKeyPath: ReferenceWritableKeyPath<EnclosingSelf, Value>,
storage storageKeyPath: ReferenceWritableKeyPath<EnclosingSelf, Self>
) -> Value {
get {
object[keyPath: storageKeyPath].value
}
set {
precondition(!object.isFrozen, "Object \(object) is frozen! Modifications are forbidden")
object[keyPath: storageKeyPath].value = newValue
}
}
}
So your class will look like:
class PhonesViewModel: NSCopying {
#Guarded
public var phoneType: PhoneNumberType = PhoneNumberType.mobile
#Guarded
public var phone: String?
#Guarded
public var code: String?
#Guarded
public var countryCode: String?
#Guarded
public var isValid : PhoneValidation?
func copy(with zone: NSZone? = nil) -> Any {
let copy = PhonesViewModel()
copy.phoneType = phoneType
copy.phone = phone
copy.code = code
copy.countryCode = countryCode
copy.isValid = isValid
return copy
}
}
I have this request:
router.get("/fetchOngoingReleases") { (request) -> Future<[ReleaseOut]> in
return Release.query(on: request).filter(\.inprogress == true).all().map { releases in
var result: [ReleaseOut] = []
for r in releases {
var pageEvents: [Event] = []
let num = r.releaseUsers.query(on: request).filter(\.user.fbId ~~ "something").count()
var needAuthentication: Bool
if num == 0 {
needAuthentication = true
} else {
needAuthentication = false
}
let rOut = ReleaseOut(fbId: r.fbId, name: r.name, purpose: r.purpose, needAuthentication: needAuthentication)
result.append(rOut)
}
return result
}
}
}
It says I can not access (???) releaseUser.user.fbId in the query?
Here the data model:
and in code
final class Release: Content {
var id: Int?
var fbId: String
var inprogress: Bool?
var name: String
var purpose: String
/// Creates a new `Release`.
init(id: Int? = nil, fbId: String, name: String, purpose: String = "normal selling") {
self.id = id
self.fbId = fbId
self.name = name
self.purpose = purpose
}
}
extension Release {
var releaseUsers: Children<Release, ReleaseUser> {
return children(\.releaseId)
}
}
final class ReleaseUser: Content {
var id: Int?
var releaseId: Release.ID
var userId: User.ID
init(id: Int? = nil, releaseId: Release.ID, userId: User.ID) {
self.id = id
self.releaseId = releaseId
self.userId = userId
}
}
extension ReleaseUser {
var user: Parent<ReleaseUser, User> {
return parent(\.userId)
}
}
final class User: Content {
var id: Int?
var fbId: String
var name: String
init(id: Int? = nil, fbId: String, name: String) {
self.id = id
self.fbId = fbId
self.name = name
}
}
Ok so there are several things going on here, but the main concept is that you can't just jump across different tables like that - you need to use a JOIN to join the ReleaseUser table to the User table so you can then query on the fbId
Try changing your query to:
Release.query(on: request).filter(\.inprogress == true).join(\ReleaseUser.releaseId, to:\Release.Id).join(\ReleaseUser.userId, to:\User.Id).alsoDecode(User.self).all()
The alsoDecode will give you a tuple with the first position containing your original Release instance and the second containing the corresponding User instance. So, fbId should be available as:
r.1.fbId
In your case.
I'm trying to migrate from CoreData to FireBase. Hence the need for a shared interface across the app for my model.
I have a FTEvent class...
#objc(FTEvent)
public class FTEvent: FTEventBase {
}
that inherits from FTEventBase
#objc(FTEventBase)
public class FTEventBase: NSManagedObject {
}
Now I have a new class called FTRecord, which should share an interface with FTEvent above.
class FTRecord {
let key: String
var notes: String
var rating: Int
var time: String
var timestamp: Double
}
This is now where the problem begins. I could obviously create a protocol as interface for both FTRecord and FTEvent.
protocol IEvent {
var is_deleted: Bool? { get set }
var notes: String? { get set }
var date: Date? { get set }
var timestamp: Double? { get set }
var rating: Int? { get set }
}
But this becomes very hard since Bool in CoreData is actually a NSNumber. The Date is NSDate. Because of these type differences, I have no way to create a common interface.
Is there any advice, how I could achieve that?
I need to use struct in my custom framework, how can the following be done?
Here my framework:
MyFramework.framework
public class SomeClass : NSObject {
public struct myDetails {
public var firstName: String?
public var lastName: String?
public init(fName: String? LastName lName: String?) {
self.firstName = fName
self.lastName = lName
}//init end
}// struct end
public func fillStruct(inout myStruct: myDetails) {
myStruct.firstName = "John"
myStruct.lastName = "Devid"
}
}// class end
Here's my Application:
// ViewController.swift
import MyFramework
var refObj: SomeClass?
override func ViewDidLoad() {
refObj = SomeClass()
let tempStruct = refObj.myDetails(fName: nil LastName lName: nil) // I CANT ABLE ACCESS LIKE THIS.
refObj.fillStruct(&tempStruct)
}
What I want, is my application to send the data to the struct and my framework to fill the struct and finish the function.
How can this be achieved?
I've got an Article and a Category model linked by a many-to-one relationship. However, the Category model has a unique constraint on the id property because it's the primary key as you can see below.
class Article: Object
{
dynamic var id: String = ""
dynamic var title: String = ""
dynamic var category: Category()
override static func primaryKey() -> String? {
return "id"
}
}
class Category: Object
{
dynamic var id: String = ""
dynamic var title: String = ""
override static func primaryKey() -> String? {
return "id"
}
}
This will work until an Article got the same Category and throw an exception because of the unique constraint.
How am I supposed to implement this kind of relationship ? Is there any built-in way to persist only the Category id and retrieve the corresponding Category ?
Thanks
As you can read in Realm doc (0.92.1), you have to use a List<Object> for a many-to-one relationship.
See this link :
http://realm.io/docs/swift/latest/
class Dog: Object {
dynamic var name = ""
dynamic var owner: Person? // Can be optional
}
class Person: Object {
... // other property declarations
let dogs = List<Dog>()
}
let someDogs = Realm().objects(Dog).filter("name contains 'Fido'")
jim.dogs.extend(someDogs)
jim.dogs.append(rex)
So in your case, I guess it should be something like that :
class Article: Object
{
dynamic var id: String = ""
dynamic var title: String = ""
override static func primaryKey() -> String? {
return "id"
}
}
class Category: Object
{
dynamic var id: String = ""
dynamic var title: String = ""
dynamic var articles = List<Article>()
override static func primaryKey() -> String? {
return "id"
}
}
If your Realm version is older :
class Category: Object
{
...
dynamic var categories = RLMArray(objectClassName: Article.className())
}