Alamofire background working on simulator but not on device - swift

Question

As the title mentions I've set up a backgroundURL with Alamofire. It works like a charm in simulator but on my device doesn't. I'm sure I'm missing something here since I'm not that experienced with URL.
Here's the code I have so far:
class NetworkManager {
static let shared = NetworkManager()
private lazy var backgroundManager: Alamofire.SessionManager = {
let bundleIdentifier = MyStruct.identifier
return Alamofire.SessionManager(configuration: URLSessionConfiguration.background(withIdentifier: bundleIdentifier))
}()
var backgroundCompletionHandler: (() -> Void)? {
get{
return backgroundManager.backgroundCompletionHandler
}
set{
backgroundManager.backgroundCompletionHandler = newValue
}
}
}
func application(_ application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: #escaping () -> Void) {
NetworkManager.shared.backgroundCompletionHandler = completionHandler
}
In my ViewController:
func populateArrays(){
Alamofire.request("http://www.aps.anl.gov/Accelerator_Systems_Division/Accelerator_Operations_Physics/sddsStatus/mainStatus.sdds.gz").responseData { response in
switch response.result{
case .success:
print("Validation Successful")
case .failure(let error):
print(error.localizedDescription)
}
if let data = response.result.value{

Answer 1

Solved it. For anyone else that has this problem you need to add the following code to your appDelegate.
func applicationDidEnterBackground(_ application: UIApplication) {
var bgTask = 0
var app = UIApplication.shared
bgTask = app.beginBackgroundTask(expirationHandler: {() -> Void in
app.endBackgroundTask(bgTask)
})

Answer 2

It seems to me that you are not using the background manager you've created. Instead of
Alamofire.request("http://www.aps.anl.gov...")
which calls the default (not background) session manager, you should use:
backgroundManager.request("http://www.aps.anl.gov...")
Which Jon Shier mentioned in the comments by the way.