Implementation of a loading spinner in swift - ios

Question

I'm attempting to show a loading spinner when I'm doing some network calls when my app first starts up from being closed. These network calls usually take a very small amount of time because they are GETs on a json string and some processing on them, but if they take longer than usual, I don't want my users trying to maneuver in the app without the data they need being there. So, I'm trying to show a spinner when these calls are going on. But the spinner never shows up. I had this working before I changed a lot of stuff, and now it's not working again, and I can't for the life of me figure out why.
Here's my viewDidLoad() method in my HomeViewController, where this information is pulled from the API and loaded into CoreData.
override func viewDidLoad() {
super.viewDidLoad()
self.showSpinner(onView: self.view)
let teamsByConferenceNetworkManager = TeamsByConferenceNetworkManager()
teamsByConferenceNetworkManager.getTeamsByConference(completion: { (data, error) in
guard let data = data else {
os_log("Could not unwrap teamsByConference data in LoginViewController.viewDidLoad()", type: .debug)
self.removeSpinner()
let _ = UIAlertAction(title: "Network unavailable", style: .cancel, handler: { (alert) in
alert.isEnabled = true
})
return
}
let dataModelManager = DataModelManager.shared
DispatchQueue.main.sync {
dataModelManager.loadTeamNamesByConference(teamNamesByConferenceName: data)
dataModelManager.loadGamesFromCoreData()
}
if let _ = dataModelManager.allGames {
self.removeSpinner()
return
} else {
let gamesNetworkManager = GamesNetworkManager()
gamesNetworkManager.getGames { (data, error) in
guard let data = data else {
os_log("Could not unwrap games data in LoginViewController.viewDidLoad()", type: .debug)
self.removeSpinner()
let _ = UIAlertAction(title: "Network unavailable", style: .cancel, handler: { (alert) in
alert.isEnabled = true
})
return
}
DispatchQueue.main.sync {
dataModelManager.loadGames(gameApiResponses: data)
}
}
}
})
self.removeSpinner()
}

Answer 1

You need to remove this
DispatchQueue.main.sync {
dataModelManager.loadGames(gameApiResponses: data)
}
}
}
})
self.removeSpinner(). <<<<<< this line
}
as the call is asynchronous and you remove the spinner directly after you add it with self.showSpinner(onView: self.view)