I would like to download from firebase:
data issued from a group profile (Firebase realtime DB)
including...
data issued from the group admin profile (Firebase realtime DB)
a group profile image (Firebase Storage)
Then I can instantiate a group object with its data and its image
First approach, I used 3 nested closures that allowed me to get data, and then to get the image.
It did work, but it was quite long to get sequentially all that stuffs from firebase.
So I tried to use GCD in order to push my 2 latest Firebase queries (user data + group image) at the same time (rather than one after the other), and to wait for the last callback to start instantiating my group.
Is it a correct approach ?
If yes, I find some difficulties to implement it...
My issue : returnedUser and returnedGroupImage are always nil
Here is my bunch of code :
static func getGroup(_ groupID:String, completionBlock: #escaping (_ group: Group?) -> ()) {
dataRef.child("data").child("groups").child(groupID).observe(.value, with: { (snapshot) in
if let snapshotValue = snapshot.value {
guard let name = (snapshotValue as AnyObject).object(forKey: "name") as? String else
{
completionBlock(nil)
return
}
guard let adminID = (snapshotValue as AnyObject).object(forKey: "adminID") as? String else
{
completionBlock(nil)
return
}
let queue = DispatchQueue(label: "asyncQueue", attributes: .concurrent, target: .main)
let dispatch_group = DispatchGroup()
var returnedUser: User?
var returnedGroupImage: UIImage?
queue.async (group: dispatch_group) {
FireBaseHelper.getUser(adminID, completionBlock: { (user) in
if user != nil {
returnedUser = user
}
})
}
queue.async (group: dispatch_group) {
FireBaseHelper.getGroupImage(groupID, completionBlock: { (image) in
if image != nil {
returnedGroupImage = image
}
})
}
dispatch_group.notify(queue: DispatchQueue.main) {
// Single callback that is supposed to be executed after all tasks are complete.
if (returnedUser == nil) || (returnedGroupImage == nil) {
// always true !
return
}
let returnedGroup = Group(knownID: (snapshotValue as AnyObject).key, named: name, createdByUser: currentUser!)
returnedGroup.groupImage = returnedGroupImage
completionBlock(returnedGroup)
}
}
})
}
Thanks for your help !
I believe that the way you are using DispatchGroups are not correct.
let dispatch_group = DispatchGroup()
var returnedUser: User?
var returnedGroupImage: UIImage?
dispatch_group.enter()
FireBaseHelper.getUser(adminID, completionBlock: { (user) in
if user != nil {
returnedUser = user
}
dispatch_group.leave()
})
dispatch_group.enter()
FireBaseHelper.getGroupImage(groupID, completionBlock: { (image) in
if image != nil {
returnedGroupImage = image
}
dispatch_group.leave()
})
dispatch_group.notify(queue: DispatchQueue.main) {
// Single callback that is supposed to be executed after all tasks are complete.
if (returnedUser == nil) || (returnedGroupImage == nil) {
// always true !
return
}
let returnedGroup = Group(knownID: (snapshotValue as AnyObject).key, named: name, createdByUser: currentUser!)
returnedGroup.groupImage = returnedGroupImage
completionBlock(returnedGroup)
}
Related
I currently have a function that allows me to upload an image to Firebase Storage. But how in the world can I achieve the same, with a video instead of an image?
I suspect I have to change UIImage and .jpg to something else. But what is the type of a video?
#State var pickedImages: [UIImage] = []
#State var retrievedImages = [UIImage]()
This is my function:
func uploadImage() {
// Create storage reference
let storageRef = Storage.storage().reference()
// Turn our image into data
let selectedImage = pickedImages[0]
let imageData = selectedImage.jpegData(compressionQuality: 0.8)
guard imageData != nil else {
let er = "THIS: Error while converting to data"
return print(er)
}
// Specifie filepath and name
let path = "images/\(UUID().uuidString).jpg"
let fileRef = storageRef.child(path)
// Upload that data
let uploadTask = fileRef.putData(imageData!, metadata: nil) {metaData, error in
print("THIS: from uploadTAsk")
// Check for errors
if error == nil && metaData != nil {
// Save reference in firestore DB
let db = Firestore.firestore()
db.collection("images").document("user1").setData(["url": path]) { error in
print("THIS: inside closure")
// If there was no errors, display the image
if error == nil {
DispatchQueue.main.async {
self.retrievedImages.append(selectedImage)
}
}
}
}
}
}
Summary
I'm developing an application where users can reserve and cancel reservations for classes. In a ReservationButtonView I two buttons that add and remove a user to a workout class respectively. Currently the button I show is based off whether the user's Firebase Auth uid is listed in a Firestore document.
I was having issues when rapidly tapping on the reservation button. Specifically, the reservationCnt would become inaccurate by showing more or less than the actual users reserved for a class.
The only way I have found to resolve this is be using a Firestore transaction that checks to see if a user is in a workout class already. If they are, addReservation() now does nothing. If they aren't, removeReservation() would also do nothing.
At first I thought I could just disable the button and via the logic still in place the code below (.disabled()), but that alone didn't work as I ran into the above described race conditions. What I found out is that arrayUnion and arrayRemove still succeed even when the object I'm looking to add is there and not there respectively. Meaning it is possible for my transaction to not remove a reservedUser that isn't there and also decrease the reservationCnt which can leave me with say no reserved users and a reservationCnt of -1
The Ask
Is there a better way to handle this reservation process? Can I accomplish this without a transaction for at least the removal of users in some way. Ideally, I'd like to have a spinner replace the button as I add or remove a user's reservation to indicate to the user that the app is processing the request. Perhaps I need two variables to manage the disabled() state instead of one?
MVVM Code Snippets
NOTE: I pulled out some button styling to make the code a bit less verbose
ReservationButtonView
struct ReservationButtonView: View {
var workoutClass: WorkoutClass
#ObservedObject var viewModel: WorkoutClassViewModel
#EnvironmentObject var authViewModel: AuthViewModel
var body: some View {
if checkIsReserved(uid: authViewModel.user?.uid ?? "", reservedUsers: workoutClass.reservedUsers ?? []) {
Button(action: {
viewModel.isDisabled = true
viewModel.removeReservation(
documentId: workoutClass.id!,
reservedUserDetails: ["uid": authViewModel.user?.uid as Any, "photoURL": authViewModel.user?.photoURL?.absoluteString ?? "" as Any, "displayName": authViewModel.user?.displayName ?? "Bruin Fitness Member" as Any],
uid: authViewModel.user?.uid ?? "")
}){
Label(
title: { Text("Cancel Reservation")
.font(.title) },
icon: { Image(systemName: "person.badge.minus")
.font(.title) }
)
}.disabled(viewModel.isDisabled)
} else{
Button(action: {
viewModel.isDisabled = true
viewModel.addReservation(
documentId: workoutClass.id!,
reservedUserDetails: ["uid": authViewModel.user?.uid as Any, "photoURL": authViewModel.user?.photoURL?.absoluteString ?? "" as Any, "displayName": authViewModel.user?.displayName ?? "Bruin Fitness Member" as Any],
uid: authViewModel.user?.uid ?? "")
}){
Label(
title: { Text("Reserve")
.font(.title) },
icon: { Image(systemName: "person.badge.plus")
.font(.title) }
)
}
.disabled(viewModel.isDisabled)
}
}
}
func checkIsReserved(uid: String, reservedUsers: [reservedUser]) -> Bool {
return reservedUsers.contains { $0.uid == uid }
}
WorkoutClassModel
struct reservedUser: Codable, Identifiable {
var id: String = UUID().uuidString
var uid: String
var photoURL: URL?
var displayName: String?
enum CodingKeys: String, CodingKey {
case uid
case photoURL
case displayName
}
}
struct WorkoutClass: Codable,Identifiable {
#DocumentID var id: String?
var reservationCnt: Int
var time: String
var workoutType: String
var reservedUsers: [reservedUser]?
enum CodingKeys: String, CodingKey {
case id
case reservationCnt
case time
case workoutType
case reservedUsers
}
}
WorkoutClassViewModel
class WorkoutClassViewModel: ObservableObject {
#Published var isDisabled = false
private var db = Firestore.firestore()
func addReservation(documentId: String, reservedUserDetails: [String: Any], uid: String){
let incrementValue: Int64 = 1
let increment = FieldValue.increment(incrementValue)
let addUser = FieldValue.arrayUnion([reservedUserDetails])
let classReference = db.document("schedules/Redwood City/dates/\(self.stateDate.dbDateFormat)/classes/\(documentId)")
db.runTransaction { transaction, errorPointer in
let classDocument: DocumentSnapshot
do {
print("Getting classDocument for docId: \(documentId) in addReservedUser()")
try classDocument = transaction.getDocument(classReference)
} catch let fetchError as NSError {
errorPointer?.pointee = fetchError
return nil
}
guard let workoutClass = try? classDocument.data(as: WorkoutClass.self) else {
let error = NSError(
domain: "AppErrorDomain",
code: -3,
userInfo: [
NSLocalizedDescriptionKey: "Unable to retrieve workoutClass from snapshot \(classDocument)"
]
)
errorPointer?.pointee = error
return nil
}
let isReserved = self.checkIsReserved(uid: uid, reservedUsers: workoutClass.reservedUsers ?? [])
if isReserved {
print("user is already in class so therefore can't be added again")
return nil
} else {
transaction.updateData(["reservationCnt": increment, "reservedUsers": addUser], forDocument: classReference)
return nil
}
} completion: { object, error in
if let error = error {
print(error.localizedDescription)
self.isDisabled = false
} else {
print("Successfully ran transaction with object: \(object ?? "")")
self.isDisabled = false
}
}
}
func removeReservation(documentId: String, reservedUserDetails: [String: Any], uid: String){
let decrementValue: Int64 = -1
let decrement = FieldValue.increment(decrementValue)
let removeUser = FieldValue.arrayRemove([reservedUserDetails])
let classReference = db.document("schedules/Redwood City/dates/\(self.stateDate.dbDateFormat)/classes/\(documentId)")
db.runTransaction { transaction, errorPointer in
let classDocument: DocumentSnapshot
do {
print("Getting classDocument for docId: \(documentId) in addReservedUser()")
try classDocument = transaction.getDocument(classReference)
} catch let fetchError as NSError {
errorPointer?.pointee = fetchError
return nil
}
guard let workoutClass = try? classDocument.data(as: WorkoutClass.self) else {
let error = NSError(
domain: "AppErrorDomain",
code: -3,
userInfo: [
NSLocalizedDescriptionKey: "Unable to retrieve reservedUsers from snapshot \(classDocument)"
]
)
errorPointer?.pointee = error
return nil
}
let isReserved = self.checkIsReserved(uid: uid, reservedUsers: workoutClass.reservedUsers ?? [] )
if isReserved {
transaction.updateData(["reservationCnt": decrement, "reservedUsers": removeUser], forDocument: classReference)
return nil
} else {
print("user not in class so therefore can't be removed")
return nil
}
} completion: { object, error in
if let error = error {
print(error.localizedDescription)
self.isDisabled = false
} else {
print("Successfully ran removeReservation transaction with object: \(object ?? "")")
self.isDisabled = false
}
}
}
func checkIsReserved(uid: String, reservedUsers: [reservedUser]) -> Bool {
return reservedUsers.contains { $0.uid == uid }
}
}
App screenshot
Reservation button is the green/grey button at the bottom of the view
As this is a race condition, You have already acknowledged the use of Transactions for the update which is the most desirable as this can ensure the update is successful before allowing the App to change button status.
I.e. by using a transaction and only updating the UI Button state on success, which is explained here
The recommendation is to keep the state of the button mapped to what is in the document, therefore you are likely to exceed rate limits by updating the same field continuously based on the flipping of the button.
Another way to handle this tracking of the state of enrollment is to add a new document that indicates the state of the enrollment for the user to a collection that is the class they are enrolling in.
I.e. Rather than having the class user enrolling into being a document, make that a collection and each time the enrollment state changes, write a new document. This will allow for updates to occur without using transactions and the current state of enrollments is contained within the latest document. This latest document can be read and used as the status of the button within the App with the added benefit that the state will always update to the status contained within Firestore.
I ended up resolving this by adding a disable check conditional before the conditional that decides whether to show the "Reserve" or "Cancel" button.
This way when my Firestore transaction is running the user will see a spinner instead and can't monkey test the button. The spinner helps to show that the reservation operation is in progress. When the transaction hits its completion block I disable the isDisabled Bool and the listener is in sync (the user then sees the newly toggled button state)
if workoutClassVM.isDisabled {
ProgressView()
.progressViewStyle(CircularProgressViewStyle(tint: Color("bruinGreenColor")))
} else if checkIsReserved(uid: authVM.user?.uid ?? "", reservedUsers: workoutClass.reservedUsers ?? []) {
...
I have the following code that fetches a schedule
func fetchSchedule(completion: #escaping () -> ()) {
scheduleRef.queryOrderedByValue().queryEqual(toValue: true).observe(.value, with: { snapshot in
self.schedule = []
if snapshot.value is NSNull {
// Null
} else {
for child in snapshot.children {
if let snapshot = child as? DataSnapshot,
let schedule = Schedule(snapshot: snapshot) {
self.schedule.append(schedule)
}
}
}
})
}
The above get the current schedule but what I am unclear on is that i need that value to then call the next function call which get the associated games for that schedule on the .onAppear() of the view in SwiftUI
func getGames() {
scheduleStore.fetchSchedule()
//
gameStore.fetchGames(weekId: self.scheduleStore.schedule[0].weekId)
}
the gameStore.fetchGames always returns null, likely because it has not finished processing the fetchSchedule function?
How do I ensure the first function finishes before it calls the fetchGames?
You have a completion handler built into your function signature on fetchSchedule, but you aren't using it.
func fetchSchedule(completion: #escaping () -> ()) {
scheduleRef.queryOrderedByValue().queryEqual(toValue: true).observe(.value, with: { snapshot in
self.schedule = []
if snapshot.value is NSNull {
// Null
} else {
for child in snapshot.children {
if let snapshot = child as? DataSnapshot,
let schedule = Schedule(snapshot: snapshot) {
self.schedule.append(schedule)
}
}
completion() //<-- Here
}
})
}
Then,
func getGames() {
scheduleStore.fetchSchedule(completion: {
gameStore.fetchGames(weekId: self.scheduleStore.schedule[0].weekId)
})
}
You're not showing all of your code, but you may also have something broken between self.schedule, which you set in fetchSchedule, and self.scheduleStore, you you send to fetchGames -- make sure you've only got one place you're storing data -- should it be self.schedule in both places?
Update, based on comments
This code is approximate, since I don't have access to your types, but it should get you started:
func fetchSchedule(completion: #escaping ([Schedule]) -> ()) {
scheduleRef.queryOrderedByValue().queryEqual(toValue: true).observe(.value, with: { snapshot in
if snapshot.value is NSNull {
// Null
} else {
let schedules = snapshot.children.compactMap { child in
if let snapshot = child as? DataSnapshot, let schedule = Schedule(snapshot: snapshot) {
return schedule
}
return nil
}
completion(schedules)
}
})
}
func getGames() {
scheduleStore.fetchSchedule { schedules in
gameStore.fetchGames(weekId: schedules[0].weekId)
}
}
Below is the code for my signup page. I want to make it so that when someone creates an account on the sign up page, I create a document in the users collection and include uuid in the document. However, session.session?.uid ends up being nil. Does anyone know why this is?
struct SignUpView: View {
#State var email = ""
#State var password = ""
#State var name = ""
#State var error = ""
#EnvironmentObject var session: SessionStore
func signUp() {
let db = Firestore.firestore()
let user = db.collection("users").document()
let test = db.collection("users").document(user.documentID).collection("routines").document()
session.signUp(email: email, password: password) { (result, error) in
if let error = error {
self.error = error.localizedDescription
print("This is the error \(error)")
return
} else {
self.email = ""
self.password = ""
}
}
user.setData(["id": user.documentID, "email": email]) { (err) in
if err != nil {
print((err?.localizedDescription)!)
return
}
}
print(session.session?.uid)
test.setData(["id:": test.documentID, "msg": "samwell Tarly", "uuid": session.session?.uid]) { (err) in
print("ummmmm test data?")
if err != nil {
print((err?.localizedDescription)!)
return
}
}
}
The Firebase APIs are asynchronous, simply because they access a remote system, across the internet, which takes a little time. The same applies for accessing the local disk, by the way. This blog post explains this in more detail.
Consequently, session.signUp is an asynchronous process. I.e. the call to print(session.session?.uid) is executed before session.signUp returns. Thus, session.session?.uid is still nil.
To work around this, you can nest your calls like this:
session.signUp(email: email, password: password) { (result, error) in
if let error = error {
self.error = error.localizedDescription
print("This is the error \(error)")
return
}
else {
self.email = ""
self.password = ""
user.setData(["id": user.documentID, "email": email]) { (err) in
if err != nil {
print((err?.localizedDescription)!)
return
}
}
}
}
Generally speaking, I would strongly recommend to not perform so much logic in your views, but instead keep your views as anaemic as possible - meaning: put all your logic into view models, and bind the view to the view models by using Combine. This will make your code much cleaner, easier to test, and maintainable.
See https://peterfriese.dev/replicating-reminder-swiftui-firebase-part2/ for how to do this.
In my application the main entity is threads, I mean sneakers, jackets, t-shorts and so on.
This is firebase db:
I have logic witch fetch threads by 'threadTypes'. In my app there're 3 types - outwear, footwear and accessory.
That is code:
extension GoodsViewController {
func fetchThreads(completion: #escaping (Swift.Void) -> Swift.Void) {
self.ref
.child("threads")
.observeSingleEvent(of: .value, with: { (snapshot) in
for rest in snapshot.children.allObjects as! [FIRDataSnapshot] {
guard let restDict = rest.value as? [String: Any] else { continue }
let thread = Thread()
thread.setValuesForKeys(restDict)
if Search.searchFilters.stuffTypes.isEmpty {
self.threads.append(thread)
}
else {
if let threadType = thread.threadType {
if Search.searchFilters.stuffTypes.contains(threadType) {
self.threads.append(thread)
}
}
}
}
completion()
})
}
}
self.threads - is variable which is used as table view datasource.
Search.searchFilters.stuffTypes - array which contains types for search.
As you see I fetch all threads and then check if current thread type contains in Search.searchFilters.stuffTypes array.
My question is - is it possible to perform this checking before I fetch all threads?
In C# it should be something like that -
threads.Where(t => Search.searchFilters.stuffTypes.Contains(t.threadType)