How to get an error response with driver so I can show it in alert. When I see the trait driver is can't error out, so should I use subject or behaviourRelay to get error response when I subscribe. Actually I like how to use driver but I don't know how to passed error response using driver.
this is my network service
func getMovies(page: Int) -> Observable<[MovieItem]> {
return Observable.create { observer -> Disposable in
self.service.request(endpoint: .discover(page: page)) { data, response, error in
if let _ = error {
observer.onError(MDBError.unableToComplete)
return
}
guard let response = response as? HTTPURLResponse, response.statusCode == 200 else {
observer.onError(MDBError.invalidResponse)
return
}
guard let data = data else {
observer.onError(MDBError.invalidData)
return
}
if let decode = self.decode(jsonData: MovieResults.self, from: data) {
observer.onNext(decode.results)
}
observer.onCompleted()
}
return Disposables.create()
}
}
This is my viewModel
protocol ViewModelType {
associatedtype Input
associatedtype Output
func transform(input: Input) -> Output
}
class PopularViewModel: ViewModelType {
struct Input {
let viewDidLoad: Driver<Void>
}
struct Output {
let loading: Driver<Bool>
let movies: Driver<[MovieItem]>
}
private let service: NetworkDataFetcher
init(service: NetworkDataFetcher = NetworkDataFetcher(service: NetworkService())) {
self.service = service
}
func transform(input: Input) -> Output {
let loading = ActivityIndicator()
let movies = input.viewDidLoad
.flatMap { _ in
self.service.getMovies(page: 1)
.trackActivity(loading)
.asDriver(onErrorJustReturn: [])
}
let errorResponse = movies
return Output(loading: loading.asDriver(),movies: movies)
}
}
this is how I bind the viewModel in viewController
let input = PopularViewModel.Input(viewDidLoad: rx.viewDidLoad.asDriver())
let output = viewModel.transform(input: input)
output.movies.drive { [weak self] movies in
guard let self = self else { return }
self.populars = movies
self.updateData(on: movies)
}.disposed(by: disposeBag)
output.loading
.drive(UIApplication.shared.rx.isNetworkActivityIndicatorVisible)
.disposed(by: disposeBag)
You do this the same way you handled the ActivityIndicator...
The ErrorRouter type below can be found here.
This is such a common pattern that I have created an API class that takes care of this automatically.
class PopularViewModel: ViewModelType {
struct Input {
let viewDidLoad: Driver<Void>
}
struct Output {
let loading: Driver<Bool>
let movies: Driver<[MovieItem]>
let displayAlertMessage: Driver<String>
}
private let service: NetworkDataFetcher
init(service: NetworkDataFetcher = NetworkDataFetcher(service: NetworkService())) {
self.service = service
}
func transform(input: Input) -> Output {
let loading = ActivityIndicator()
let errorRouter = ErrorRouter()
let movies = input.viewDidLoad
.flatMap { [service] in
service.getMovies(page: 1)
.trackActivity(loading)
.rerouteError(errorRouter)
.asDriver(onErrorRecover: { _ in fatalError() })
}
let displayAlertMessage = errorRouter.error
.map { $0.localizedDescription }
.asDriver(onErrorRecover: { _ in fatalError() })
return Output(
loading: loading.isActive.asDriver(onErrorRecover: { _ in fatalError() }),
movies: movies,
displayAlertMessage: displayAlertMessage
)
}
}
I built an MVVM architecture to support my app which is supposed to control the pipeline between the frontend and my firebase database. Initially, I successfully implemented the entire work by coding totally in the frontend, but there are lots of bugs when I encapsulated them into a function.
For example, the next sheet will be presented when the currently presented sheet gets dismissed. Sometimes I needed to wait for a long time until the app is unfrozen. Even worse, the app crashed down when I clicked the button.
I heard that nested models don't work yet if SwiftUI is in use (reference). However, I just cannot come up with a better solution if my classes are untested.
// This is Model
import Foundation
import SwiftUI
struct userModel {
var uid = UUID()
var name = ""
var bio = ""
var interest = ""
var level = 1
var xp = 0
var email = ""
var image: Data = Data(count: 0)
init() {
}
init(_ name:String, _ xp: Int) {
self.name = name
self.xp = xp
self.level = self.xp2Level(xp: xp)
}
func xp2Level(xp:Int) -> Int {
if xp < 9500 {
return xp / 500 + 1
}
else if xp < 29500 {
return (xp - 9500) / 1000 + 1
}
else {
return (xp - 29500) / 2000 + 1
}
}
}
// This is ViewModel
import Foundation
import SwiftUI
import Firebase
class userViewModel: ObservableObject {
#Published var user: userModel = userModel()
#Published var isLoading = false
#AppStorage("status") var status = false
private var ref = Firestore.firestore()
private let store = Storage.storage().reference()
var picker = false
func updateXP(completion: #escaping () -> Int) -> Int {
guard let uid = Auth.auth().currentUser?.uid else {
return 0
}
// catch the information of the current user
let db = ref.collection("Users")
db.addSnapshotListener { [self] (querySnapshot, error) in
guard (querySnapshot?.documents) != nil else {
print("Document is empty")
return
}
let docRef = db.document(uid)
docRef.getDocument { (snapshot, error) in
if let doc = snapshot,
let xp = doc.get("xp") as? Int {
self.user.xp = xp
}
}
}
return completion()
}
func updateLevel(completion: #escaping () -> Int) -> Int {
guard let uid = Auth.auth().currentUser?.uid else {
return 1
}
// catch the information of the current user
let db = ref.collection("Users")
db.addSnapshotListener { [self] (querySnapshot, error) in
guard (querySnapshot?.documents) != nil else {
print("Document is empty")
return
}
let docRef = db.document(uid)
docRef.getDocument { (snapshot, error) in
if let doc = snapshot,
let level = doc.get("level") as? Int {
self.user.level = level
}
}
}
return completion()
}
func updateName (completion: #escaping () -> String) -> String {
guard let uid = Auth.auth().currentUser?.uid else {
return ""
}
// catch the information of the current user
let db = ref.collection("Users")
db.addSnapshotListener { [self] (querySnapshot, error) in
guard (querySnapshot?.documents) != nil else {
print("Document is empty")
return
}
let docRef = db.document(uid)
docRef.getDocument { (snapshot, error) in
if let doc = snapshot,
let name = doc.get("username") as? String {
self.user.name = name
}
}
}
return completion()
}
func updateBio (completion: #escaping () -> String) -> String {
guard let uid = Auth.auth().currentUser?.uid else {
return ""
}
// catch the information of the current user
let db = ref.collection("Users")
db.addSnapshotListener { [self] (querySnapshot, error) in
guard (querySnapshot?.documents) != nil else {
print("Document is empty")
return
}
let docRef = db.document(uid)
docRef.getDocument { (snapshot, error) in
if let doc = snapshot,
let bio = doc.get("bio") as? String {
self.user.bio = bio
}
}
}
return completion()
}
func updateInterest (completion: #escaping () -> String) -> String {
guard let uid = Auth.auth().currentUser?.uid else {
return ""
}
// catch the information of the current user
let db = ref.collection("Users")
db.addSnapshotListener { [self] (querySnapshot, error) in
guard (querySnapshot?.documents) != nil else {
print("Document is empty")
return
}
let docRef = db.document(uid)
docRef.getDocument { (snapshot, error) in
if let doc = snapshot,
let interest = doc.get("interest") as? String {
self.user.interest = interest
}
}
}
return completion()
}
func updatePhoto (completion: #escaping () -> Data) -> Data {
guard let uid = Auth.auth().currentUser?.uid else {
return Data(count: 0)
}
// catch the information of the current user
let db = ref.collection("Users")
db.addSnapshotListener { [self] (querySnapshot, error) in
guard (querySnapshot?.documents) != nil else {
print("Document is empty")
return
}
let docRef = db.document(uid)
docRef.getDocument { (snapshot, error) in
if snapshot != nil {
let imageRef = store.child("profile_Photos").child(uid)
imageRef.getData(maxSize: 1000 * 64 * 64, completion: { (data, error) in
if let error = error {
print("Encountered error: \(error) when getting image")
self.user.image = Data(count: 0)
} else if let data = data,
!data.isEmpty{
// self.currentUser.image = Image(uiImage: UIImage(data: data)!).resizable()
self.user.image = data
} else {
// self.currentUser.image = Image(systemName: "person").resizable()
self.user.image = Data(count: 0)
}
})
} else if let error = error {
print(error)
}
}
}
return completion()
}
public func getXP() -> Int{
updateXP {
return (self.user.xp) as Int
}
}
public func getLevel() -> Int {
updateLevel(completion: {
return (self.user.level) as Int
})
}
public func getName() -> String {
updateName(completion: {
return (self.user.name) as String
})
}
public func getBio() -> String {
updateBio(completion: {
return (self.user.bio) as String
})
}
public func getInterest() -> String {
updateInterest(completion: {
return (self.user.interest) as String
})
}
public func getPhoto() -> Data {
updatePhoto(completion: {
return (self.user.image) as Data
})
}
func updatePersonalInfo() {
//sending user data to Firebase
let uid = Auth.auth().currentUser?.uid
isLoading = true
self.uploadImage(imageData: self.getPhoto(), path: "profile_Photos") { (url) in
self.ref.collection("Users").document(uid ?? "").setData([
"uid": uid ?? "",
"imageurl": url,
"username": self.user.name,
"bio": self.user.bio,
"interest" : self.user.interest
], merge: true) { (err) in
if err != nil{
self.isLoading = false
return
}
self.isLoading = false
// success means settings status as true...
self.status = true
}
}
}
func increaseXPnLV() {
//sending user data to Firebase
let uid = Auth.auth().currentUser!.uid
let docRef = ref.collection("Users").document(uid)
docRef.getDocument { (document, error) in
if let document = document, document.exists {
docRef.updateData(["xp": FieldValue.increment(Int64(50))])
// update level
let xp = document.data()!["xp"] as! Int
docRef.updateData(["level": self.user.xp2Level(xp: xp)])
} else {
print("Document does not exist")
}
}
}
func uploadImage(imageData: Data, path: String, completion: #escaping (String) -> ()){
let storage = Storage.storage().reference()
let uid = Auth.auth().currentUser?.uid
storage.child(path).child(uid ?? "").putData(imageData, metadata: nil) { (_, err) in
print("imageData: \(imageData)")
if err != nil{
completion("")
return
}
// Downloading Url And Sending Back...
storage.child(path).child(uid ?? "").downloadURL { (url, err) in
if err != nil{
completion("")
return
}
completion("\(url!)")
}
}
}
}
// This is View
import SwiftUI
import CoreData
import Firebase
import FirebaseFirestore
struct Goals: View {
let current_user_id = Auth.auth().currentUser?.uid
#State private var showingAlert = false
var ref = Firestore.firestore()
#StateObject var currentUser: userViewModel
#StateObject var homeData = HomeViewModel()
#State var txt = ""
#State var edge = UIApplication.shared.windows.first?.safeAreaInsets
#FetchRequest(entity: Goal.entity(), sortDescriptors: [NSSortDescriptor(key: "date",
ascending: true)], animation: .spring()) var results : FetchedResults<Goal>
// let timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
#State private var greeting : String = "Hello"
#Environment(\.managedObjectContext) var context
var body: some View {
ForEach(results){goal in
Button(action: {
context.delete(goal)
try! context.save()
if current_user_id != nil {
currentUser.updateXPnLV()
self.showingAlert = true
}
}, label: Text("Something")
)
.alert(isPresented: $showingAlert) {
() -> Alert in
Alert(title: Text("Congratulations!"), message: Text("You completed a goal today, XP+50!"), dismissButton: .default(Text("OK")))
}
}
}
}
EDIT
Another error I saw is AttributeGraph precondition failure: attribute failed to set an initial value: 805912, ForEachChild<Array<userInfoModel>, ObjectIdentifier, HStack<VStack<HStack<TupleView<(Text, Divider, Text)>>>>>.
AppStorage is for use in a View while it may appear to be working all the SwiftUI wrappers with the exception of #Published inside an ObservableObject seem to be unreliable outside of a struct that is a View.
https://developer.apple.com/documentation/swiftui/appstorage
As a standard practice all your class and struct should be capitalized so change class CurrentUserViewModel andclass UserInfoModel
Also, change #StateObject var currentUser: currentUserViewModel to #StateObject var currentUser: CurrentUserViewModel = CurrentUserViewModel()
The initialization is the most important part that is missing.
Everything in the ForEach is just floating it isn't within a variable, function or inside the body. Where is your body?
This is probably what the error is talking about. wrap all of that code in a body
var body: some View {
//All the code for the ForEach
}
Your Button seems to be missing a title or label
Remove this line
() -> Alert in
I am sure there are other little things. I suggest you start from scratch in this View and you start putting in code line by line.
Here is a starting point. The Firebase part needs quite a but of work but you should be able to get started by focusing on the code that I commented out and removing the code to mimic a response from Firebase.
All of this is in the FirebaseManager class
Once this is working the rest will work.
The code as is works so you can see it in action with the fake responses
///Keep all the Firebase Code HERE
class FirebaseManager{
//private var ref = Firestore.firestore()
//private let store = Storage.storage().reference()
func retrieveFromDB(collectionName: String, variableName: String, completion: #escaping (Result<Any, Error>) -> Void) {
print(#function)
//This is sample code, likely has errors because I dont have Firebase setup but you can see the logic so you can touch up
// guard let uid = Auth.auth().currentUser?.uid else {
// completion(.failure(FirebaseError.notLoggedIn))
// return
// }
// catch the information of the current user
// let db = ref.collection(collectionName)
// db.addSnapshotListener { [self] (querySnapshot, error) in
//
// if let error = error{
// completion(.failure(error))
// return
// }
// guard (querySnapshot?.documents) != nil else {
// print("Document is empty")
// completion(.failure(FirebaseError.emptyDocument))
// return
// }
// let docRef = db.(document(uid)
//
// docRef.getDocument { (snapshot, error) in
// if let error = error{
// completion(.failure(error))
// return
// }
//
// completion(.success(snapshot.get(variableName)))
// }
// }
//For sample purposes I will mimic response remove this in your actual code
DispatchQueue.main.async {
if variableName == "xp" || variableName == "level"{
completion(.success(Int.random(in: 0...200)))
}else{
let strings = ["apple", "orange", "banana", "kiwi", "startfruit"]
completion(.success(strings.randomElement()!))
}
}
}
///For Int variables
func retrieveFromUsers(variableName: String, completion: #escaping (Result<Int, Error>) -> Void) {
print(#function)
retrieveFromDB(collectionName: "Users", variableName: variableName, completion: {result in
switch result {
case .success(let value):
let xp = value as? Int
if xp != nil{
completion(.success(xp!))
}else{
completion(.failure(FirebaseError.wrongType))
}
return
case .failure(let error):
print(error)
completion(.failure(error))
}
})
}
///For String variables
func retrieveUserProperty(variableName: String, completion: #escaping (Result<String, Error>) -> Void) {
print(#function)
retrieveFromDB(collectionName: "Users", variableName: variableName, completion: {result in
switch result {
case .success(let value):
let username = value as? String
if username != nil{
completion(.success(username!))
}else{
completion(.failure(FirebaseError.wrongType))
}
return
case .failure(let error):
print(error)
completion(.failure(error))
}
})
}
func retrieveXP(completion: #escaping (Result<Int, Error>) -> Void) {
print(#function)
retrieveFromUsers(variableName: "xp", completion: completion)
}
func retrieveLevel(completion: #escaping (Result<Int, Error>) -> Void) {
print(#function)
retrieveFromUsers(variableName: "level", completion: completion)
}
func retrieveName (completion: #escaping (Result<String, Error>) -> Void) {
print(#function)
retrieveUserProperty(variableName: "username", completion: completion)
}
func retrieveBio (completion: #escaping (Result<String, Error>) -> Void) {
print(#function)
retrieveUserProperty(variableName: "bio", completion: completion)
}
func retrieveInterest (completion: #escaping (Result<String, Error>) -> Void) {
print(#function)
retrieveUserProperty(variableName: "interest", completion: completion)
}
//Database code to retrieve Image needs to be added
func updateDB(collectionName: String, variableName: String, incrementBy: Int, completion: #escaping (Result<Int, Error>) -> Void) {
print(#function)
//sending user data to Firebase
// let uid = Auth.auth().currentUser!.uid
// let docRef = ref.collection(collectionName).document(uid)
// docRef.getDocument { (document, error) in
// if let document = document, document.exists {
// docRef.updateData([variableName: FieldValue.increment(incrementBy)])
//let newValue = document.data()![variableName] as! Int
// completion(.success(newValue))
// } else {
// completion(.failure(FirebaseError.documentDoesntExist))
// }
// }
//For sample purposes I will mimic response remove this in your actual code
DispatchQueue.main.async {
completion(.success(Int.random(in: 0...200) + incrementBy))
}
}
func updateDB(collectionName: String, variableName: String, value: String, completion: #escaping (Result<String, Error>) -> Void) {
print(#function)
//sending user data to Firebase
// let uid = Auth.auth().currentUser!.uid
// let docRef = ref.collection(collectionName).document(uid)
// docRef.getDocument { (document, error) in
// if let document = document, document.exists {
// docRef.updateData([variableName: value])
//let newValue = document.data()![variableName] as! Int
// completion(.success(newValue))
// } else {
// completion(.failure(FirebaseError.documentDoesntExist))
// }
// }
//For sample purposes I will mimic response remove this in your actual code
DispatchQueue.main.async {
let strings = ["apple", "orange", "banana", "kiwi", "startfruit"]
completion(.success(strings.randomElement()!))
}
}
func updateDB(collectionName: String, variableName: String, value: Int, completion: #escaping (Result<Int, Error>) -> Void) {
print(#function)
//sending user data to Firebase
// let uid = Auth.auth().currentUser!.uid
// let docRef = ref.collection(collectionName).document(uid)
// docRef.getDocument { (document, error) in
// if let document = document, document.exists {
// docRef.updateData([variableName: value])
//let newValue = document.data()![variableName] as! Int
// completion(.success(newValue))
// } else {
// completion(.failure(FirebaseError.documentDoesntExist))
// }
// }
//For sample purposes I will mimic response
DispatchQueue.main.async {
completion(.success(Int.random(in: 0...200)))
}
}
func updateUsers(variableName: String, value: String, completion: #escaping (Result<String, Error>) -> Void) {
print(#function)
updateDB(collectionName: "Users", variableName: variableName, value: value, completion: completion)
}
func updateUsers(variableName: String, value: Int, completion: #escaping (Result<Int, Error>) -> Void) {
print(#function)
updateDB(collectionName: "Users", variableName: variableName, value: value, completion: completion)
}
func updateUsers(variableName: String, incrementBy: Int, completion: #escaping (Result<Int, Error>) -> Void) {
print(#function)
updateDB(collectionName: "Users", variableName: variableName, incrementBy: incrementBy, completion: completion)
}
//Code to update Image will need to be added
}
Here is the rest
import SwiftUI
import CoreData
//Capitalized no other changes here
struct UserModel {
var uid = UUID()
var name = ""
var bio = ""
var interest = ""
var level = 1
var xp = 0
var email = ""
var image: Data = Data(count: 0)
init() {
print(#function)
}
init(_ name:String, _ xp: Int) {
print(#function)
self.name = name
self.xp = xp
self.level = self.xp2Level(xp: xp)
}
func xp2Level(xp:Int) -> Int {
print(#function)
if xp < 9500 {
return xp / 500 + 1
}
else if xp < 29500 {
return (xp - 9500) / 1000 + 1
}
else {
return (xp - 29500) / 2000 + 1
}
}
}
//This is to standardize what comes from your Firebase Code. Try to condense code that is duplicated
enum FirebaseError: Error {
case notLoggedIn
case emptyDocument
case wrongType
case documentDoesntExist
}
Capitalize
class UserViewModel: ObservableObject {
let alertVM = AlertViewModel.shared
#Published var user: UserModel = UserModel()
#Published var isLoading = false
//AppStorage wont work here
var status: Bool{
get{
UserDefaults.standard.bool(forKey: "status")
}
set{
UserDefaults.standard.set(newValue, forKey: "status")
}
}
//Separate all Firebase Code
let firebaseManager = FirebaseManager()
init() {
populateAllVariables()
}
func increaseXPnLV() {
print(#function)
//sending xp to Firebase
firebaseManager.updateUsers(variableName: "xp", incrementBy: 50, completion: {result in
switch result {
case .success(let newXp):
self.user.xp = newXp
//sending level to Firebase
self.firebaseManager.updateUsers(variableName: "level", value: self.user.xp2Level(xp: newXp), completion: {result in
switch result {
case .success(let newLevel):
print("newLevel = \(newLevel)")
self.user.level = newLevel
self.alertVM.scheduleAlert(title: "Congratulations!", message: "You completed a goal today, XP+50!")
return
case .failure(let error as NSError):
//Show alert here
self.alertVM.scheduleAlert(error: error)
print(error)
}
})
return
case .failure(let error):
//Show alert here
self.alertVM.scheduleAlert(error: error)
print(error)
}
})
}
func populateAllVariables() {
print(#function)
getXP()
getLevel()
getName()
getBio()
getInterest()
}
public func getXP() {
print(#function)
firebaseManager.retrieveXP(completion: {result in
switch result {
case .success(let xp):
self.user.xp = xp
case .failure(let error):
//Show alert here
self.alertVM.scheduleAlert(error: error)
print(error)
}
})
}
public func getLevel() {
print(#function)
firebaseManager.retrieveLevel(completion: {result in
switch result {
case .success(let level):
self.user.level = level
case .failure(let error):
//Show alert here
self.alertVM.scheduleAlert(error: error)
print(error)
}
})
}
public func getName() {
print(#function)
firebaseManager.retrieveName(completion: {result in
switch result {
case .success(let name):
self.user.name = name
case .failure(let error):
//Show alert here
self.alertVM.scheduleAlert(error: error)
print(error)
}
})
}
public func getBio() {
print(#function)
firebaseManager.retrieveBio(completion: {result in
switch result {
case .success(let bio):
self.user.bio = bio
case .failure(let error):
//Show alert here
self.alertVM.scheduleAlert(error: error)
print(error)
}
})
}
public func getInterest() {
print(#function)
firebaseManager.retrieveInterest(completion: {result in
switch result {
case .success(let interest):
self.user.interest = interest
case .failure(let error):
//Show alert here
self.alertVM.scheduleAlert(error: error)
print(error)
}
})
}
///This will need work
// public func getPhoto() -> Data {
// updatePhoto(completion: {
// return (self.user.image) as Data
// })
// }
//It is best to separate work from the View
func deleteGoal(moc: NSManagedObjectContext, goal: Goal) -> Bool{
print(#function)
var result = false
moc.performAndWait {
moc.delete(goal)
do{
try moc.save()
result = true
}catch{
self.alertVM.scheduleAlert(error: error)
result = false
}
}
return result
}
}
//This is to centralize alerts. When you are using the web there will be errors and therefore alerts that the user should be aware of
struct CustomAlert: Identifiable {
let id: UUID = UUID()
let title: String
let message: String
let dismissButtonTitle: String
}
//Again to centralize the alerts. I like putting this on the uppermost View so you can send alerts from anywhere
class AlertViewModel: ObservableObject {
//Singleton keeps everything connected
static let shared: AlertViewModel = AlertViewModel()
#Published var currentAlert: CustomAlert?
private init() {
//Required because you need to share the instance
}
//Use this for a custom message
func scheduleAlert(title: String = "ERROR", message: String, dismissButtonTitle: String = "OK") {
currentAlert = CustomAlert(title: title, message: message, dismissButtonTitle: dismissButtonTitle)
}
//Use this if you have a fully formed Error
func scheduleAlert(error: Error) {
let error = error as NSError
currentAlert = CustomAlert(title: "ERROR", message: (error.localizedFailureReason ?? "") + error.localizedDescription + (error.localizedRecoverySuggestion ?? ""), dismissButtonTitle: "OK")
}
}
struct Goals: View {
//The View should never be aware of where your data is stored. all Firebase code should be removed
#StateObject var currentUser: UserViewModel = UserViewModel()
//This observes the alerts that are sent from anywhere
#StateObject var alertVM: AlertViewModel = AlertViewModel.shared
//No code provided
//#StateObject var homeData = HomeViewModel()
#FetchRequest(entity: Goal.entity(), sortDescriptors: [NSSortDescriptor(keyPath: \Goal.date, ascending: true)], animation: .spring()) var results : FetchedResults<Goal>
#Environment(\.managedObjectContext) var context
var body: some View {
VStack{
Text("Name = " + currentUser.user.name.description)
Text("Level = " + currentUser.user.level.description)
Text("XP = " + currentUser.user.xp.description)
ForEach(results){goal in
Button(action: {
//There should be some kind of check here to make sure the goal got deleted
if currentUser.deleteGoal(moc: context, goal: goal){
//No code provided
//if current_user_id != nil {
currentUser.increaseXPnLV()
}
//}
}, label: {
//Missing Brackets
Text("Goal \(goal.name?.description ?? "") Completed")
})
//This gets presented from everywhere
.alert(item: $alertVM.currentAlert, content: {current in
Alert(title: Text(current.title), message: Text(current.message), dismissButton: .cancel(Text(current.dismissButtonTitle)))
})
}
}
}
}
This question already has answers here:
How do i return coordinates after forward geocoding?
(3 answers)
block until reverseGeocode has returned
(1 answer)
Closed 1 year ago.
I am new with swift. For my project I need to use google geocoding and to put the result in a text. For the user interface I am using swiftUI. I tried to do the same with Completition Handler but that didn't work. Below I have the code done with DispatchQueue and DispatchGroup but the whole application freezes when I try to use this func. Please help me with this. The code for UI is just a Text calling the func.
func reverseGeocoding(lat: Double, lng: Double) -> String{
var place:String?
let url = "https://maps.googleapis.com/maps/api/geocode/json?latlng=\(lat),\(lng)&key=KEY"
let group = DispatchGroup()
group.enter()
DispatchQueue.global(qos: .default).async {
AF.request(url).responseJSON{ response in
// group.leave()
guard let data = response.data else {
return
}
do {
let jsonData = try JSON(data: data)
let result = jsonData["results"].arrayValue
for result in result {
let address_components = result["types"].arrayValue
for component in address_components {
if(component == "locality"){
place = result["formatted_address"].stringValue
}
}
}
} catch let error {
print(error.localizedDescription)
}
}
}
group.wait()
return place ?? ""
}
continuation for #vadian answer
As mentioned in the above publisher depends on context .This will give you a rough idea.This is from what I understood..
// Replace String with [String] if you want to add multiple locations at once based on it Publisher.send() accepts [String] instead of String
var LocationPublisher = PassthroughSubject<String,Never>()
class Subscriber :ObservableObject {
#Published var currentLocation :[String] = Array<String>()
private var cancellebels = Set< AnyCancellable>()
func createSubscriber(){
let subscriber = LocationPublisher.handleEvents(
receiveSubscription: {subscription in
print("New subscription \(subscription)")},
receiveOutput: {output in
print("New Output \(output)")
},
receiveCancel: {
print("Subscription Canceled")
})
.receive(on: RunLoop.main)
// if you replace String with [String],TypeOf(value) becomes [String]
.sink{value in
print("Subscriber recieved value \(value)")
self.currentLocation.append(value)
// use self.currenLocation.append(contentsOf:value) instead
}
.store(in: &cancellebels)
}
init() {
createSubscriber()
}
}
And inside this contentView
struct ContentView: View {
#ObservedObject var locationObject:Subscriber = Subscriber()
var body: some View {
VStack{
List{
locationObject.currentLocation.forEach{ location in
Text(location)
}
}
}
}
}
and from the above answer inside the success completion handler use
LocationPublisher.send(location)
instead of print statement
it will be notified to subscribers and locationObject.currentLocation will be updated
Its just one way to do it and most basic way.
You need a completion handler like this, it returns also all errors in the Result type
enum GeoError : Error {
case locationNoFound
}
func reverseGeocoding(lat: Double, lng: Double, completion: #escaping (Result<String,Error>) -> Void) {
let url = "https://maps.googleapis.com/maps/api/geocode/json?latlng=\(lat),\(lng)&key=KEY"
DispatchQueue.global(qos: .default).async {
AF.request(url).responseData { response in
switch response.result {
case .success(let data):
do {
let jsonData = try JSON(data: data)
let result = jsonData["results"].arrayValue
for result in result {
let addressComponents = result["types"].arrayValue
for component in addressComponents {
if component == "locality" {
completion(.success(result["formatted_address"].stringValue))
}
}
}
completion(.failure(GeoError.locationNoFound))
} catch {
completion(.failure(error))
}
case .failure(let error):
completion(.failure(error))
}
}
}
}
And use it
reverseGeocoding(lat: 45.0, lng: 45.0) { result in
switch result {
case .success(let location): print(location)
case .failure(let error): print(error)
}
}
I have this Networking class that i declared in the Model .
class Networking {
func response (url : String ) {
guard let url = URL(string: url) else {return}
URLSession.shared.dataTask(with: url, completionHandler: urlPathCompletionHandler(data:response:error:)).resume()
}
func urlPathCompletionHandler (data : Data? , response: URLResponse? , error: Error? ) {
guard let data = data else {return }
do {
let jsondecoder = JSONDecoder()
}catch {
print("Error \(error)")
}
}
}
In the controller . I have an array of users i declared and i want the controller to call from the Model Networking class instead of doing the networking inside the controller. This is part of my controller:
var users = [Users]()
var networking : Networking()
#IBOutlet weak var tableview : UITableView!
override func viewDidLoad() {
super.viewDidLoad()
tableview.delegate = self
tableview.dataSource = self
}
func getFromModel() {
var vm = networking.response()
}
I want a way of calling the networking class and return an array of users that i can set to the users array above and use it to populate the table view . If i wanted to do that inside the controller it would easy but i am not sure how i can return an array of users from the Model Networking class .
You need to modify your Network class like this:
class Networking {
func response<T: Codable>(url: String, completion: ((T) -> Void)?) {
guard let url = URL(string: url) else {return}
URLSession.shared.dataTask(with: url, completionHandler: { (data, response, error) in
self.urlPathCompletionHandler(data: data, response: response, error: error, completion: completion)
}).resume()
}
func urlPathCompletionHandler<T: Codable>(data : Data? , response: URLResponse? , error: Error?, completion: ((T) -> Void)?) {
guard let data = data else { return }
do {
let jsondecoder = JSONDecoder()
// Pseudo Code to decode users
completion?(decodedObject)
} catch {
print("Error \(error)")
}
}
}
And call it like this:
func getFromModel() {
networking.response(url: <#T##String#>) { (users: [User]) in
self.users = users
}
}
OK, there are a few thoughts:
Your response method is performing an asynchronous network request, so you need to give it a completion handler parameter. So, I might suggest something like:
class Networking {
enum NetworkingError: Error {
case invalidURL
case failed(Data?, URLResponse?)
}
private let parsingQueue = DispatchQueue(label: Bundle.main.bundleIdentifier! + ".parsing")
// response method to handle network stuff
func responseData(_ string: String, completion: #escaping (Result<Data, Error>) -> Void) {
guard let url = URL(string: string) else {
completion(.failure(NetworkingError.invalidURL))
return
}
URLSession.shared.dataTask(with: url) { data, response, error in
DispatchQueue.main.async {
if let error = error {
completion(.failure(error))
return
}
guard
let responseData = data,
let httpResponse = response as? HTTPURLResponse,
200 ..< 300 ~= httpResponse.statusCode
else {
completion(.failure(NetworkingError.failed(data, response)))
return
}
completion(.success(responseData))
}
}.resume()
}
// response method to handle the JSON parsing
func response<T: Decodable>(of type: T.Type, from string: String, completion: #escaping (Result<T, Error>) -> Void) {
responseData(string) { result in
switch result {
case .failure(let error):
completion(.failure(error))
case .success(let data):
self.parsingQueue.async {
do {
let responseObject = try JSONDecoder().decode(T.self, from: data)
DispatchQueue.main.async {
completion(.success(responseObject))
}
} catch let parseError {
DispatchQueue.main.async {
completion(.failure(parseError))
}
}
}
}
}
}
}
This obviously assumes that you have some Codable types. For example, it’s common for an API to have some common structure in its responses:
struct ResponseObject<T: Decodable>: Decodable {
let code: Int
let message: String?
let data: T?
}
And maybe the User is like so:
struct User: Decodable {
let id: String
let name: String
}
Then getFromModel (perhaps better called getFromRepository or something like that) could parse it with:
networking.response(of: ResponseObject<[User]>.self, from: urlString) { result in
switch result {
case .failure(let error):
print(error)
case .success(let responseObject):
let users = responseObject.data
// do something with users
}
}
For what it’s worth, if you didn’t want to write your own networking code, you could use Alamofire, and then getFromModel would do:
AF.request(urlString).responseDecodable(of: ResponseObject<[User]>.self) { response in
switch response.result {
case .failure(let error):
print(error)
case .success(let responseObject):
let users = responseObject.data
}
}
Now, clearly the model types are likely to be different in your example, but you didn’t share what your JSON looked like, so I had to guess, but hopefully the above illustrates the general idea. Make a generic-based network API and give it a completion handler for its asynchronous responses.
How to use call getEmployee function while using "Result"?
struct Employee {
let name: String
let designation: String
}
func getEmployee(name: String, completion: #escaping(Result<Employee?, Error>) -> Void) {
}
First you need to make your structure conform to Codable
struct Employee: Codable {
let name, designation: String
}
Than you need to fetch your data from your server and call completion if decoding was successful with your employee .success(employee) or if it fails pass failure with your error .failure(error):
func getEmployee(name: String, completion: #escaping(Result<Employee, Error>) -> Void) {
URLSession.shared.dataTask(with: URL(string: "http://www.example.com/getEmployee.api?name=\(name)")!) { data, response, error in
guard let data = data, error == nil else {
if let error = error { completion(.failure(error)) }
return
}
do {
let employee = try JSONDecoder().decode(Employee.self, from: data)
completion(.success(employee))
} catch {
completion(.failure(error))
}
}
}
Usage:
getEmployee(name: "Ella") { result in
switch result {
case let .success(employee):
print("employee:", employee)
case let .failure(error):
print("error:", error)
default: break
}
}