Extract value from task in Swift 3 - swift

Question

I have a problem when trying to parse a simple website in Swift 3. I combined what I found on this website, but still can't extract loginText from the other function, and got a 'instance member can't be used on .. type' error when trying to put everything into a class.
import Foundation
import PlaygroundSupport
PlaygroundPage.current.needsIndefiniteExecution = true
extension String {
func slice(from: String, to: String) -> String? {
return (range(of: from)?.upperBound).flatMap { substringFrom in
(range(of: to, range: substringFrom..<endIndex)?.lowerBound).map { substringTo in
substring(with: substringFrom..<substringTo)
}
}
}
}
var loginText = ""
func getToken(completionHandler: (String) -> () ) {
var request = URLRequest(url: URL(string: [MY URL])!)
request.httpMethod = "GET"
var loginText = ""
let sessionConfig = URLSessionConfiguration.default
let session = URLSession(configuration: sessionConfig)
let task = session.dataTask(with: request) {data, response, err in
loginText = (String(data: data!, encoding: String.Encoding.utf8)!)
}
task.resume()
}
func viewDidLoad() {
getToken {
loginText in
loginText.slice(from: "LT", to: "1s1")
print("View Controller: \(loginText)")
}
}
print(viewDidLoad())
print(loginText)
Thanks !

Answer 1

I got you.
You are coincidentally using the wrong loginText.
You called the completionHandler string loginText while also having loginText declared outside the function.
But you were on the right path.
Your problem will be solved if you call self.loginText, check this out:
getToken {
loginText in //you named it loginText
self.loginText.slice(from: "LT", to: "1s1")
print("View Controller: \(loginText)")
}
The thing is, this STILL never gets called. Because you are never calling that completionHandler, also -
forget about self.loginText, because you have a completionHandler that just passes your string.
Use this and don't even change the getToken method. It will be called, and will work fine:
let task = session.dataTask(with: request) {data, response, err in
let loginText = (String(data: data!, encoding: String.Encoding.utf8)!)
completionHandler(loginText)
}
Also I would delete the var loginText = "" if you don't want to use it outside of getToken. But even if you are, I would suggest just having a function which takes in a String, rather then having it declared just outside. But you know why you need it outside if you do - so yeah. Cheers
EDIT: You also seem to be missing the #escaping
func getToken(completionHandler: #escaping (String) -> () ) {}