I'm using the Realm to save some objects and the user has the ability to reload them through a network function.
class Task: Object {
dynamic var id: String = ""
dynamic var price: Double = 0
override class func primaryKey() -> String {
return "id"
}
func fillNew(json: JSON) {
self.id = json["id"].stringValue
self.name = json["prive"].doubleValue
}
}
The network function get an array of json to build these objects. Once these new objects are created, I pass them through an add or update but when I fetch them again the fields have not changed.
func getPendingTasks(completion: (JSON?, NSError?) -> ()) {
let urlString = ".."
Alamofire.request(.GET, urlString).responseJSON { response in
let json = response.result.value != nil ? JSON(response.result.value!) : nil
dispatch_async(dispatch_get_main_queue()) {
completion(json, response.result.error)
}
}
}
func getTasks() {
self.getPendingTasks() { json, error in
if let error = error {
return
}
let jsonTasks = json!["tasks"].arrayValue
for jsonTask in jsonTasks {
let task = Task()
task.fillNew(jsonTask)
self.tasks.append(task);
}
self.tasks = Task.sortGenericTasks(self.tasks)
dispatch_async(dispatch_get_main_queue()) {
let realm = try! Realm()
try! realm.write {
realm.add(self.tasks, update: true)
}
}
}
}
I'm currently using the latest version of realm, but can not pinpoint exactly what is happening or if I'm doing something wrong.
Related
I am trying to make an API call to the GitLab API to get the projects that are available to a particular user.
I can get one project of an index of my choosing, put it into a ProjectModel with the projectId and the projectName but I can not figure out how to get all of them into an array of ProjectModels.
By printing then I can see them all being printed in the console but it will not let me append them to an array.
It is in the parseJSON function that I am trying to get a hold of all of the projects.
Does anyone have any suggestions?
This is my manager to fetch the projects:
protocol FetchProjectsManagerDelegate {
func didUpdateProjects(_ fetchProjectsManager: FetchProjectsManager, project: ProjectModel?)
func didFailWithError(error: Error)
}
struct FetchProjectsManager {
let projectsURL = "secret"
var delegate: FetchProjectsManagerDelegate?
func fetchProjects(privateToken: String) {
let privateTokenString = "\(projectsURL)projects?private_token=\(privateToken)"
performRequest(with: privateTokenString)
}
func performRequest(with privateTokenString: String) {
// Create url
if let url = URL(string: privateTokenString) {
// Create URLSession
let session = URLSession(configuration: .default)
// Give the session a task
let task = session.dataTask(with: url) { data, response, error in
if error != nil {
self.delegate?.didFailWithError(error: error!)
return
}
if let safeData = data {
if let project = self.parseJSON(safeData) {
self.delegate?.didUpdateProjects(self, project: project)
}
}
}
// Start the task
task.resume()
}
}
func parseJSON(_ projectData: Data) -> ProjectModel? {
let decoder = JSONDecoder()
do {
let decodedData = try decoder.decode([Project].self, from: projectData)
for project in decodedData {
print(project)
}
let projectId = decodedData[0].id
let projectName = decodedData[0].name
let project = ProjectModel(projectId: projectId, projectName: projectName)
return project
} catch {
delegate?.didFailWithError(error: error)
return nil
}
}
}
This is my project model
struct ProjectModel {
let projectId: Int
let projectName: String
}
Your parseJson method only returns a single project instead of all of them, change it to
func parseJSON(_ projectData: Data) -> [ProjectModel]? {
let decoder = JSONDecoder()
do {
let decodedData = try decoder.decode([Project].self, from: projectData)
let projects = decodedData.map { ProjectModel(projectId: $0.id,
projectName: $0.name) }
return projects
} catch {
delegate?.didFailWithError(error: error)
return nil
}
}
and you of course need to update didUpdateProjects so that it takes an array of ProjectModel or call it in a loop
I am trying to save "author" data to global variable named "authors" from json(Link:"https://learnappmaking.com/ex/books.json") with these two libraries. But it only works at the trailing closure of func Alamofire.request(url).responseJSON. When I access the global variable named "authors" from somewhere except the trailing closure, what I get is an empty array of string.
Can someone explain the reason behind this werid situation？
Thanks a lot.
class ViewController: UIViewController {
var authors = [String]()
let url = "https://learnappmaking.com/ex/books.json"
func getAuthorsCount() {
print("the number of authors : \(authors.count)") // I hope that here, the number of authors should be 3 too! actually, it is 0. Why?
// this for loop doesn't get excuted
for author in authors {
print(author)
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
Alamofire.request(url).responseJSON { response in
if let data = response.data {
if let json = try? JSON(data: data) {
for item in json["books"].arrayValue {
var outputString: String
print(item["author"])
outputString = item["author"].stringValue
//urlOfProjectAsset.append(outputString)
self.authors.append(outputString)
print("authors.count: \(self.authors.count)")
}
}
}
}
getAuthorsCount()
print("-------------")
}
}
the actual output is:
Update：
I adjusted my code:
class ViewController: UIViewController {
var authors = [String]()
let url = "https://learnappmaking.com/ex/books.json"
func getAuthorsCount() {
print("the number of authors : \(authors.count)")
// this for loop doesn't get excuted
for author in authors {
print(author)
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
Alamofire.request(url).responseJSON { response in
if let data = response.data {
if let json = try? JSON(data: data) {
for item in json["books"].arrayValue {
var outputString: String
//print(item["author"])
outputString = item["author"].stringValue
//urlOfProjectAsset.append(outputString)
self.authors.append(outputString)
//print("authors.count: \(self.authors.count)")
}
self.getAuthorsCount() // I added this line of code.
}
}
}
getAuthorsCount()
print("-------------")
}
}
But why does the func getAuthorsCount() (not self. version) still print an empty array of strings ? I think the result should be the same as the result which
func self.getAuthorsCount() printed.
I am so confused now...
Again, I want to use the data kept in the variable named "authors", but what I only got is an empty array of strings.
I'll try to answer all your questions :
The data is persistant
You are doing the following : Alamo.request (Network call) -> getAuthors(print result - empty) ->
response (receive response) -> self.authors.append(save response) -> self.authors (print result)
You need to do : Alamo.request (Network call) -> response (receive response) -> self.authors.append(save response) -> self.getAuthors or getAuthors(same) (inside the response {})
You need to call getAuthors once you have your result, inside the response callback :
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
Alamofire.request(url).responseJSON { response in
if let data = response.data {
if let json = try? JSON(data: data) {
for item in json["books"].arrayValue {
var outputString: String
print(item["author"])
outputString = item["author"].stringValue
//urlOfProjectAsset.append(outputString)
self.authors.append(outputString)
print("authors.count: \(self.authors.count)")
}
self.getAuthorsCount()
print("-------------")
//Do whatever you want from here : present/push
}
}
}
Then you can use the saved data :
To send the data to another ViewController you can use various methods (present/push, closure/callback, ...)
Usually you will have a loading spinner to wait for the network to
answer then you will show your next controller
As requested via direct message: a Swift-only approach. Just paste this in a blank Playground:
import Foundation
final class NetworkService {
enum ServiceError: LocalizedError {
case invalidUrl
case networkingError(error: Error)
case parsingError
var localizedDescription: String? { return String(describing: self) }
}
func request(completion: #escaping (Result<[UserObject], Error>) -> Void ) {
guard let url = URL(string: "https://jsonplaceholder.typicode.com/users") else {
completion(.failure(ServiceError.invalidUrl))
return
}
let dataTask = URLSession.shared.dataTask(with: url) { (jsonData, response, error) in
if let jsonData = jsonData {
let jsonDecoder = JSONDecoder()
do {
let users = try jsonDecoder.decode([UserObject].self, from: jsonData)
completion(.success(users))
} catch {
completion(.failure(ServiceError.parsingError))
}
} else if let error = error {
completion(.failure(ServiceError.networkingError(error: error)))
}
}
dataTask.resume()
}
}
struct UserObject: Codable {
let id: Int
let name: String
let username: String
let email: String?
let website: String?
}
let networkService = NetworkService()
networkService.request { result in
switch result {
case .success(let users):
debugPrint("Received \(users.count) users from REST API")
debugPrint(users)
case .failure(let error):
debugPrint(error.localizedDescription)
}
}
I am trying to load data from a GET request using Alamofire library in swift and cannot append data from the requests. I am trying to populate an array of orders to load into a UITableView.
I have tried a few various ways of solving this issue but nothing is working for me. I have commented out the method I tried because with 2 separate calls to fetchAll...Orders and the second call always overwrites the first and then the tableView is loaded with missing items.
class DrinkOrdersTableViewController: UITableViewController {
var orders: [Order] = []
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.title = "Current Orders"
}
override func viewWillAppear(_ animated: Bool) {
// fetchAllBeerOrders { orders in
// self.orders = orders!
// //print("Beer fetch: ", self.orders)
// self.tableView.reloadData()
// }
// fetchAllCocktailOrders { orders in
// self.orders = orders!
// //print("Cocktail fetch: ", self.orders)
// self.tableView.reloadData()
// }
fetchAllBeerOrders { orders in
self.orders.append(orders)
self.tableView.reloadData()
}
fetchAllCocktailOrders { orders in
self.orders.append(orders)
self.tableView.reloadData()
}
}
private func fetchAllCocktailOrders(completion: #escaping([Order]?) -> Void) {
Alamofire.request("http://127.0.0.1:4000/orders", method: .get)
.validate()
.responseJSON { response in
guard response.result.isSuccess else { return completion(nil) }
guard let rawInventory = response.result.value as? [[String: Any]?] else { return completion(nil) }
let currentOrders = rawInventory.compactMap { ordersDict -> Order? in
guard let orderId = ordersDict!["id"] as? String,
let orderStatus = ordersDict!["status"] as? String,
var pizza = ordersDict!["cocktail"] as? [String: Any] else { return nil }
pizza["image"] = UIImage(named: pizza["image"] as! String)
return Order(
id: orderId,
pizza: Pizza(data: pizza),
status: OrderStatus(rawValue: orderStatus)!
)
}
completion(currentOrders)
}
}
private func fetchAllBeerOrders(completion: #escaping([Order]?) -> Void) {
Alamofire.request("http://127.0.0.1:4000/orders", method: .get)
.validate()
.responseJSON { response in
guard response.result.isSuccess else { return completion(nil) }
guard let rawInventory = response.result.value as? [[String: Any]?] else { return completion(nil) }
let currentOrders = rawInventory.compactMap { ordersDict -> Order? in
guard let orderId = ordersDict!["id"] as? String,
let orderStatus = ordersDict!["status"] as? String,
var pizza = ordersDict!["pizza"] as? [String: Any] else { return nil }
pizza["image"] = UIImage(named: pizza["image"] as! String)
return Order(
id: orderId,
pizza: Pizza(data: pizza),
status: OrderStatus(rawValue: orderStatus)!
)
}
completion(currentOrders)
}
}
As of right now I am getting this error with code above: Cannot convert value of type '[Order]?' to expected argument type 'Order'. The ideal outcome of this code is to have the data that is gathered from each GET request to append to the array of Orders. I have verified that the GET requests are working and giving back the correct data. Please Help :]
You declared orders of type [Order] and your fetch methods compilation blocks return [Order]?. As you can see, you cannot convert value of type [Order]? to expected argument type Order when you wrote self.orders.append(orders).
To fix these, put a guard unwrap in fetch method invocations.
fetchAllBeerOrders { orders in
guard let _orders = orders else { return }
self.orders.append(_orders)
self.tableView.reloadData()
}
fetchAllCocktailOrders { orders in
guard let _orders = orders else { return }
self.orders.append(_orders)
self.tableView.reloadData()
}
Now, you have a potential memory leak in your code. fetchAllBeerOrders and fetchAllCocktailOrders are async methods with compilation blocks. You cannot use a strong reference to self here. Use weak to avoid a memory leak, like:
fetchAllBeerOrders { [weak self] orders in
guard let _orders = orders else { return }
self?.orders.append(_orders)
self?.tableView.reloadData()
}
fetchAllCocktailOrders { [weak self] orders in
guard let _orders = orders else { return }
self?.orders.append(_orders)
self?.tableView.reloadData()
}
I have update DataBase in background. My data can contain ~2000 items and it take time to update.
func updateData(items: [JSON], _ complete:#escaping() -> Void) {
DispatchQueue.global(qos: .userInitiated).async {
let currentModels = EgrnModel.getAllModels()
var newModels: [EgrnModel] = []
var toDelete: [EgrnModel] = []
for model in currentModels {
let contain = items.contains(where: {$0["id"].intValue == model.id})
if !contain {
toDelete.append(model)
}
}
let realm = try! Realm()
try! realm.write {
for item in items {
if let model = currentModels.first(where: {$0.id == item["id"].intValue}) {
model.update(item)
}
else {
newModels.append(EgrnModel(item))
}
}
realm.delete(toDelete)
realm.add(newModels)
}
DispatchQueue.main.async {
complete()
}
}
}
and I have a function in which I need update data momentarily. When I tap checkmark I have a freeze. (I think it because at this time other data is updating in background)
func checkMark(index: Int) {
let model = models[index]
let realm = try! Realm()
try! realm.write {
model.needToUpdateOnServer = true
model.lastEditUpdate = Date()
model.read = true
}
}
I try next code to fix a freeze. But in this code I have a crash Terminating app due to uncaught exception 'RLMException', reason: 'Realm accessed from incorrect thread.
func checkMark(index: Int) {
let model = models[index]
DispatchQueue.global(qos: .userInitiated).async {
let realm = try! Realm()
try! realm.write {
model.needToUpdateOnServer = true
model.lastEditUpdate = Date()
model.read = true
}
}
}
What you need to is "move" realm objects from one thread to another because realm objects are not thread-safe but Thread Confined. To achieve this you have to use ThreadSafeReference API.
To solve this problem do the following:
Create an extension on the realm class
extension Realm {
func writeAsync<T : ThreadConfined>(obj: T, errorHandler: #escaping ((_ error : Swift.Error) -> Void) = { _ in return }, block: #escaping ((Realm, T?) -> Void)) {
let wrappedObj = ThreadSafeReference(to: obj)
let config = self.configuration
DispatchQueue(label: "background").async {
autoreleasepool {
do {
let realm = try Realm(configuration: config)
let obj = realm.resolve(wrappedObj)
try realm.write {
block(realm, obj)
}
}
catch {
errorHandler(error)
}
}
}
}
}
Use it in your code this way
func checkMark(index: Int) {
let model = models[index]
let realm = try! Realm()
realm.asyncWrite(model) { realm, model in
model.needToUpdateOnServer = true
model.lastEditUpdate = Date()
model.read = true
}
}
HAPPY SWIFTING!
I have a enormous json file and I am trying to extract information form the file, but it is way to big to track down the path. Could I filter it using the id? JSON code I need to pick up course names i.e.
let urlString = "Can't provide the url"
if let url = NSURL(string: urlString){
if let data = try? NSData(contentsOfURL: url, options: []){
let json = JSON(data: data)
parseJSON(json)
}
}
}
func parseJSON(json: JSON){
for (index: String, subJson: JSON) in json {
}
}
I came up with a depth-first way of finding a given JSON object based on a predicate.
I made it into an extension:
extension JSON {
func find(#noescape predicate: JSON -> Bool) -> JSON? {
if predicate(self) {
return self
}
else {
if let subJSON = (dictionary?.map { $0.1 } ?? array) {
for json in subJSON {
if let foundJSON = json.find(predicate) {
return foundJSON
}
}
}
}
return nil
}
}
For instance, to search for the JSON object with a given id field, such as in the question, you can use the method as such:
let json = JSON(data: data)
let predicate = {
(json: JSON) -> Bool in
if let jsonID = json["id"].string where jsonID == "plnMain_ddlClasses" {
return true
}
return false
}
let foundJSON = json.find(predicate)
In this case, if you need to continue and find the classes you were looking for, you would want:
let classes = foundJSON?["children"].arrayValue.map {
$0["html"].stringValue
}
UPDATE — FIND ALL
func findAll(#noescape predicate predicate: JSON -> Bool) -> [JSON] {
var json: [JSON] = []
if predicate(self) {
json.append(self)
}
if let subJSON = (dictionary?.map{ $0.1 } ?? array) {
// Not using `flatMap` to keep the #noescape attribute
for object in subJSON {
json += object.findAll(predicate: predicate)
}
}
return json
}