I've trying to reorder objects from at TableView in a Realm utility class. Many other Stack Overflow questions have said to uses List, however I can't seem to make it work. (Example, example). I'm able to successfully add objects to my list with:
public func addUserSong(song: Song) {
let songList = List<Song>()
songList.append(objectsIn: realm.objects(Song.self))
try! realm.write {
songList.append(song)
realm.add(songList)
}
}
However, I'm not able to preserve the updated order when trying:
public func reorder(from: Int, to: Int) {
let songs = List<Song>()
songs.append(objectsIn: realm.objects(Song.self))
songs.move(from: from, to: to)
try! realm.write {
realm.add(songs)
}
My models are:
class Song: Object {
#Persisted var name: String
#Persisted var key: String
}
class SongList: Object {
let songs = List<Song>()
}
Thanks!
Realm object order is not guaranteed. (unless you specify a sort order)
e.g. if you load 10 songs from Realm, they could come into your app an any order and the order could change between loads. The caveat to that is a Realm List object. Lists always maintain their order.
The problem in the question is you have Song objects stored in Realm but as mentioned above there is no ordering.
So the approach needs to be modified by leveraging a List object for each user to keep track of their songs:
class UserClass: Object {
#Persisted var name: String
#Persisted var songList = List<SongClass>()
}
When adding a song to a user, call it within a write transaction
try! realm.write {
someUser.songList.append(someSong)
}
suppose the user wants to switch the place of song 2 and song 3. Again, within a write transaction:
try! realm.write {
someUser.songList.move(from: 2, to: 3)
}
So then the UI bit - tableViews are backed by a tableView dataSource - this case it would be the songList property. When that dataSource is updated, the tableView should reflect that change.
In this case you would add an observer to the someUser.songList and as the underlying data changes, the observer will react to that change and can then update the UI.
You can do something simple like tableView.reloadData() to reflect the change or if you want fine-grained changes (like row animations for example) you can do that as well. In that same guide, see the code where tableView.deleteRows, .insertRows and .reload is handled. You know what rows were changed in the underlying data there so you can then animate the rows in the tableView.
Related
My app is very similar to Tinder, and only got the "matching" part left for it to be finished. When the user touches the 'Heart' button, a card with their profile is displayed on the Notifications View to the other user, for them to accept it or not.
In case of yes, the will both 'match' as in Tinder. My problem is in how to make that happen.
Person is presented to the User, and the home view displays the people, that UserManager holds.
struct Person: Identifiable, Hashable {
var username: String
var age: Int
}
struct User {
let username: String // These are let because they're being saved on UserManager
let age: Int
}
class UserManager: ObservableObject {
#Published var userInfo: UserInfo?
#Published var people: [Person] = [] // All People
#Published var matches: [Person] = [] // Matched people
Now, here in UserManager, I fetchAllUsers from Firebase and basically init the people's data by the documentSnapshot.
ref.getDocuments { documentsSnapshot, error in
if let error = error { }
documentsSnapshot?.documents.forEach({ snapshot in
let data = snapshot.data()
self.people.append(.init(data: data))
})
}
And finally, in HomeView, the user taps the button and appends the other person in the matches array, which doesn't make sense cause the other person hasn't even accepted them yet.
struct HomeView: View {
var body: some View {
CircleButtonView(type: .heart) {
if let person = userMng.people.last {
userMng.swipe(person, _direction: .like)
userMng.matches.append(person)
// Should change this to another array?
}
}
}
}
Tried saving it to Firebase and then retrieving the data from the users once matched but I can't especify what person the user has liked, for me to make that network call.
How can I append the liked person to another array and then append it to 'matches' once confirmed that they both like each other?
You need to make a new table in firebase with the name of firendRequest, where table child id will be userID and below it, we will have ids of all users who has sent him the friends request. Please have a look the the schema in below image which will make your concept more clear.
The way, you are getting all the user will add up more computation when number of users start increasing and its not recommend to do such large computation on mobile devices. One more thing, Firesbase is NO-SQL database so you need to duplicate your data to avoid computations. Making duplicate date does not mean you are not implementing the thing right :)
I am trying to create a data model which mirrors a view model that I use to handle an API call, the idea being that I will be able to store all the necessary data in core data and then access it when the user is offline, effectively giving the app offline functionality.
However, there is one entity which I need to store which is an array of a custom class that I have in the app:
[OrderSheet]
This is a struct defined as follows:
struct OrderSheet {
let order: SheetClass // codable class
let sheet: Sheet // codable struct
init(fuelOrder: SheetClass, sheet: Sheet) {
self.order = order
self.sheet = sheet
}
}
How can I create an entity that would be capable of storing the above?
One simple way would be to have an entity that holds only one Data field (Binary Data in xcdatamodel settings), which would be the orderSheet itself.
Before going with this solution, I'd like to mention that, one down side of this approach is; if later in the future, any of the models inside OrderSheet changes, you won't be able to retrieve already stored objects as conversion will fail. One way of overcoming this issue would be declaring everything inside OrderSheet and sub models as Optional. But if it is not so crucial, meaning, if not being able to read old models on user's device after an app update is okay, (maybe they will be replaced with new networking call) then you can go with not marking properties as optional either.
Lets imagine you create an entity named OrderSheetManaged with one field as I mentioned like following:
import Foundation
import CoreData
#objc(Entity)
public class OrderSheetManaged: NSManagedObject {
}
extension OrderSheetManaged {
#nonobjc public class func fetchRequest() -> NSFetchRequest<OrderSheetManaged> {
return NSFetchRequest<OrderSheetManaged>(entityName: "OrderSheetManaged")
}
#NSManaged public var orderSheet: Data?
}
I will write some code for NSManagedObjectContext, which is not directly related to your question, you should make research on how to initialise a core data stack and a managed context from it if you are not familiar with that since it is crucial.
I also do some force unwrapping for simplicity, make sure to not force unwrap where not needed in production code.
Now whenever you have an actual OrderSheet object (it is orderSheet in my example below), that was parsed before, you are going to convert it to Data and persist it with new Core Data model as following:
// unrelated to question, it should already be initialised from core data stack, I just init with
// concurrency type to make compiler happy, dont do this before further research.
let yourManagedContext = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
let entityDescription = NSEntityDescription.entity(forEntityName: "OrderSheetManaged",
in: yourManagedContext)
let dataForCoreData = try! JSONEncoder().encode(orderSheet)
let managedOrderSheet = NSManagedObject(entity: entityDescription!, insertInto: yourManagedContext)
managedOrderSheet.setValue(dataForCoreData, forKey: "orderSheet")
Now we have persisted your object as Data inside a wrapper core data model (OrderSheetManaged)
Let's see now how we can fetch these models from our core data and convert it back to OrderSheet model:
// when you fetch it
var orderSheets = [OrderSheet]()
let request = NSFetchRequest<NSFetchRequestResult>(entityName: "OrderSheetManaged")
var coreDataObjects: [NSManagedObject]!
do {
coreDataObjects = try yourManagedContext.fetch(request) as? [NSManagedObject]
for coreDataObject in coreDataObjects {
if let orderSheetData = coreDataObject.value(forKey: "orderSheet") as? Data {
let orderSheet = try! JSONDecoder().decode(OrderSheet.self, from: orderSheetData)
orderSheets.append(orderSheet)
}
}
} catch {
error
}
Now you will have all your stored order sheets inside orderSheets array.
You can also write some utility methods to easily modify core data models by converting orderSheet data inside of them to OrderSheet first and then again converting it back to Data after modifying and then persisting again with setValue.
I'm creating an app that interacts with a Firestore database. As of now I have a singleton class, DatabaseManager that has all the methods relating to the Firestore database (i.e. get/post methods).
I have a User model called User that has properties such as name, email, photoURL, and some app-specific properties. Any user can edit their profile to update information from a view controller called EditProfileViewController.
Now my question is: is it best to call the DatabaseManager.shared.updateInfo(forUser: user) (where user is a User instance) from EditProfileViewController, User, or some other place?
Sorry if this is an obvious question, but there's going to be a lot of points in the app where I'll need similar logic so I wanted to know what's the best design. Also I'm sure this question has more to with MVC than it does Firebase/Swift.
A couple of thoughts:
Rather than accessing the singleton directly with, DatabaseManager.shared.update(for:), I might instead have a property for the database manager, initialize/inject it with the DatabaseManager.shared, and have whatever needs to interact with the database use that reference, e.g., dataManager.update(for:). The goal would be to allow your unit tests to mock a database manager if and when necessary.
I would not be inclined to have a view controller interact directly with the DatabaseManager. Many of us consider the view controller, which interacts directly with UIKit/AppKit objects, as part of the broader “V” of MVC/MVP/MVVM/whatever. We’d often extricate business logic (including interaction with the database manager) out of the view controller.
I personally wouldn’t bury it under the User object, either. I’d put it in an extension of the database manager, and called from the view model, the presenter, or whatever you personally want to call that object with the business logic.
Is there a reason you're using a singleton to contain all the Firestore logic? User model should contain the method updateInfo.
Here's an example i've used with Firestore:
class Group {
// can read the var anywhere, but an only set value in this class
private(set) var groupName: String!
private(set) var guestsInGroup: Int!
private(set) var joinedGroup: Bool!
private(set) var timeStampGroupCreated: Date!
private(set) var documentId: String!
init(groupName: String, guestsInGroup: Int, joinedGroup: Bool, timeStampGroupCreated: Date, documentId: String) {
self.groupName = groupName
self.guestsInGroup = guestsInGroup
self.joinedGroup = joinedGroup
self.timeStampGroupCreated = timeStampGroupCreated
self.documentId = documentId
}
// method to parse Firestore data to array, that table view will display
class func parseData(snapshot: QuerySnapshot?) -> [Group]{
var groups = [Group]()
guard let snap = snapshot else { return groups }
for document in snap.documents {
let data = document.data()
let groupName = data[GROUP_NAME] as? String ?? "No Group Name"
let guestsInGroup = data[GUESTS_IN_GROUP] as? Int ?? 0
let joinedGroup = data[JOINED_GROUP] as? Bool ?? false
let timeStampGroupCreated = data[TIMESTAMP_GROUP_CREATED] as? Date ?? Date()
let documentId = document.documentID
// add objects with fetched data into thoughts array
let newGroup = Group(groupName: groupName, guestsInGroup: guestsInGroup, joinedGroup: joinedGroup, timeStampGroupCreated: timeStampGroupCreated, documentId: documentId)
groups.append(newGroup)
}
return groups
}
}
I have a List<Workout> object that occasionally needs to be sorted (e.g., if a user adds a Workout out of order), but I can't seem to get the new sorted List<Workout> to persist. My code works the moment it runs (i.e., it shows up on the view as sorted), but when I exit the ViewController or restart the app, I see nothing. The nothing is due to the exercise.workoutDiary.removeAll() persisting, but apparently the subsequent assignment to the exercise.workoutDiary = sortedWorkoutDiary is not persisting. Any ideas why?
Everything else works just fine. The typical recordWorkout() case works assuming nothing is entered out of order. So the persisting is working in nearly all cases except for this overwrite of the sorted List.
The update happens here:
struct ExerciseDetailViewModel {
private let exercise: Exercise!
func recordWorkout(newWorkout: Workout) {
let lastWorkout = exercise.workoutDiary.last // grab the last workout for later comparison
let realm = try! Realm()
try! realm.write {
exercise.workoutDiary.append(newWorkout) // write the workout no matter what
}
if let secondToLastWorkout = lastWorkout { // only bother checking out of order if there is a last workout...
if newWorkout.date < secondToLastWorkout.date { // ...and now look to see if they are out of order
let sortedWorkoutDiary = exercise.sortedWorkouts
try! realm.write {
exercise.workoutDiary.removeAll()
exercise.workoutDiary = sortedWorkoutDiary
}
}
}
}
}
final class Exercise: Object {
var workoutDiary = List<Workout>()
var sortedWorkouts: List<Workout> {
return List(workoutDiary.sorted("date"))
}
}
final class Workout: Object {
dynamic var date = NSDate()
var sets = List<WorkSet>()
}
List<T> properties in Realm Swift must be mutated in place, not assigned to. The Swift runtime does not provide any way for Realm to intercept assignments to properties of generic types. Instead, you should use methods like appendContentsOf(_:) to mutate the List<T>:
exercise.workoutDiary.removeAll()
exercise.workoutDiary.appendContentsOf(sortedWorkoutDiary)
This limitation on assignment to properties of generic types is why the Realm Swift documentation recommends that you declare such properties using let rather than var. This will allow the Swift compiler to catch these sorts of mistakes.
One further note: for your sortedWorkouts computed property, it'd be preferable for it to return Results<Workout> instead to avoid allocating and populating an intermediate List<Workout>.
Full code on github
I am trying to rewrite my app to reduce mutability and take advantage of functional programming. I am having trouble figuring out where to start, since it seems like my architecture is to use modification in place almost everywhere. I could use some advice on a simple starting point of how to break this down into smaller pieces where I am maintaining immutability at each modification. Should I change my data storage architecture so that I am only storing/modifying/deleting the leaf objects?
Right now, from the root ViewController, I load my one monster object ExerciseProgram (which contains a RealmList of Exercise objects, which contains a RealmList of Workouts, which contains a RealmList of Sets....)
final class ExerciseProgram: Object {
dynamic var name: String = ""
dynamic var startDate = NSDate()
dynamic var userProfile: User?
var program = List<Exercise>()
var count: Int {
return program.count
}
}
Loaded here one time in MasterTableViewController.swift:
func load() -> ExerciseProgram? {
let realm = try! Realm()
return realm.objects(ExerciseProgram).first
}
and then modify the single ExerciseProgram object in place throughout the app, such as when recording a new workout.
To create a new Workout, I instantiate a new Workout object in RecordWorkoutTableViewController.swift:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if doneButton === sender {
if let date = newDate, weight = newWeight, setOne = newSetOne, setTwo = newSetTwo {
let newSets = List<WorkSet>()
newSets.append(WorkSet(weight: weight, repCount: setOne))
newSets.append(WorkSet(weight: weight, repCount: setTwo))
newWorkout = Workout(date: date, sets: newSets)
}
}
}
Which unwinds to ExerciseDetailTableViewController.swift where the storage occurs into the same monster ExerciseProgram object retrieved at the beginning:
#IBAction func unwindToExerciseDetail(sender: UIStoryboardSegue) {
if let sourceViewController = sender.sourceViewController as? RecordWorkoutTableViewController, newWorkout = sourceViewController.newWorkout {
let realm = try! Realm()
try! realm.write {
exercise.recordWorkout(newWorkout)
}
}
}
This behavior is replicated all over my app. If I want to edit or delete an existing workout, it's exactly the same.
The Exercise class is just this:
final class Exercise: Object {
dynamic var name = ""
dynamic var notes: String?
var workoutDiary = List<Workout>()
dynamic var goal = 0
...
func recordWorkout(newWorkout: Workout) {
workoutDiary.append(newWorkout)
}
func replaceWorkout(originalWorkout: Workout, newWorkout: Workout) {
workoutDiary[workoutDiary.indexOf(originalWorkout)!] = newWorkout
}
}
From what I can tell, looking at that schema, no, you shouldn't change it. If it's representing the types of information and their relations properly and it's already working in your app, then there's no need to change it.
If you feel it is overly complex or confusing, then it may be necessary to go back and look at your data model design itself before actually doing more work on the code itself. Review each relationship and each property in the linked objects, and make sure that it's absolutely critical that the data is saved at that level. In any case, Realm itself is very good at handling relationships between objects, so it's not 'wrong' to have several layers of nested objects.
Either way, Realm itself lends itself pretty well to functional programming since every property is explicitly immutable out of the box. Functional programming doesn't mean everything has to be immutable always though. Inevitably, you'll have to reach a point where you'll need to save changes to Realm; the mindset behind it is that you're not transforming data as you're working on it, and you minimise the number of points that actually do so.