Mutating function inside structure - swift

Question

I'm using Swift 4, I have a structure that I initialize with default values.
I made a function inside that is supposed to read a JSON and change those default values with what it gets but it doesn't seem to work.
Error: Closure cannot implicitly capture a mutating self parameter
Code:
struct Workspace: Decodable {
var guid: String
var name: String
private enum CodingKeys : String, CodingKey {
case guid = "guid"
case name = "name"
}
init(){
self.guid = "blbl"
self.name = "oops"
}
mutating func getUserWorkspace(base: String, completed: #escaping () -> ()){
let url = URL(string: "some url")!
var request = URLRequest(url: url)
request.addValue("Basic \(base)", forHTTPHeaderField: "Authorization")
request.addValue("application/json", forHTTPHeaderField: "Accept")
URLSession.shared.dataTask(with: request){ (data, response, error) in
if error == nil {
do {
let res: Workspace = try JSONDecoder().decode(Workspace.self, from: data!)
self.guid = res.guid //Error here
self.name = res.name //Error here
DispatchQueue.main.async {
completed()
}
}catch {
print ("JSON error")
}
}
}.resume()
}
I changed let to var, but I guess there's still something I don't understand..

Answer 1

//Try this one and let me know
struct Workspace: Decodable {
static var shared = Workspace()
var guid: String
var name: String
private enum CodingKeys : String, CodingKey {
case guid = "guid"
case name = "name"
}
init(){
self.guid = "blbl"
self.name = "oops"
}
mutating func getUserWorkspace(base: String, completed: #escaping () -> ()){
let url = URL(string: "some url")!
var request = URLRequest(url: url)
request.addValue("Basic \(base)", forHTTPHeaderField: "Authorization")
request.addValue("application/json", forHTTPHeaderField: "Accept")
URLSession.shared.dataTask(with: request){ (data, response, error) in
if error == nil {
do {
let res: Workspace = try JSONDecoder().decode(Workspace.self, from: data!)
Workspace.shared.guid = res.guid //Error here
Workspace.shared.name = res.name //Error here
DispatchQueue.main.async {
completed()
}
}catch {
print ("JSON error")
}
}
}.resume()
}
}

Answer 2

I would suggest you to use class instead of struct. Anyway if you like to use your code, then capture the self inside your mutation method like below:
mutating func getUserWorkspace(base: String, completed: #escaping () -> ()){
let url = URL(string: "some url")!
var request = URLRequest(url: url)
var myself = self
request.addValue("Basic \(base)", forHTTPHeaderField: "Authorization")
request.addValue("application/json", forHTTPHeaderField: "Accept")
URLSession.shared.dataTask(with: request){ (data, response, error) in
if error == nil {
do {
let res: Workspace = try JSONDecoder().decode(Workspace.self, from: data!)
myself.guid = res.guid //Error here
myself.name = res.name //Error here
DispatchQueue.main.async {
completed()
}
}catch {
print ("JSON error")
}
}
}.resume()
}

Answer 3

I actually found the problem.. and it was pretty stupid.. I just had to change the "completed" part of the function, like this:
mutating func getUserWorkspace(base: String, completed: #escaping (_ arr:[Workspace]?) -> ()){
let url = URL(string: "SOME URL")!
var request = URLRequest(url: url)
request.addValue("Basic \(base)", forHTTPHeaderField: "Authorization")
request.addValue("application/json", forHTTPHeaderField: "Accept")
URLSession.shared.dataTask(with: request){ (data, response, error) in
if error == nil {
do {
let rep = try JSONDecoder().decode([Workspace].self, from: data!)
DispatchQueue.main.async {
completed(rep)
}
}catch {
print(error)
}
}
}.resume()
}