How to load tab bar controller from login view - Swift - swift

Question

So I made a view controller for login user with Parse. when the user login by entering the log in button, tab bar view controller load. The issue is if the user open the app and he already login, I don't want him to go without entering his login. I want the signing view controller send him to tab bar view controller.
The initial view controller is Tab bar view controller, I tried many ways to deal with this problem, but nothing seems good.
waiting for all you thoughts.

Answer 1

There are probably a lot of different ways you can achieve this, but one way I've dealt with this type of situation in the past is to create a custom container ViewController. This VC doesn't have a UIView of its own, but instead presents other ViewControllers as its "Views".
Here's a link to some Apple documentation that describes creating a controller of this type.
One of the benefits of this architecture is that I always have a VC in-scope that can take action to reroute my user based on events related to their account status (not logged in, offline limit reached, account suspended, first-time user, logout, etc.).
EDIT: Example Container Controller
Here's an example of how to implement a custom container controller. I'm sure there are some better ways to do a few of the features shown here, but hopefully this gives you a good start.
import UIKit
class ApplicationContainerController: UIViewController {
//MARK: - View Controller Routing Properties
private var _currentClientView:UIView? = nil
private var _currentViewController: UIViewController? = nil
//MARK: - Initialization
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
//MARK: - UIViewController Members
override func viewDidLoad() {
super.viewDidLoad()
}
override var shouldAutomaticallyForwardAppearanceMethods : Bool {
return true
}
override func viewWillAppear(_ animated: Bool) {
//Get the user and route to the appropriate VC
let yourUserObject: AnyObject? = YourDataSource.TryToGetAUser()
DispatchQueue.main.async {
self.routeUser(yourUserObject)
}
}
//MARK: - Your Custom Routing Logic
func routeUser(_ yourUserObject: AnyObject?) {
//make sure we have an existing user, or else we send them to login
guard let user = yourUserObject
else {
self.displayContentController(YourLoginViewController())
return
}
var destinationViewController:UIViewController
//please use an enum or something (instead of strings) in your code
switch user.signInStatus {
case "loginActive":
let mainMenuViewController = YourMainMenuViewController()
mainMenuViewController.user = user
destinationViewController = mainMenuViewController
case "firstLogin":
let firstLoginViewController = YourFirstLoginViewController()
firstLoginViewController.user = user
destinationViewController = firstLoginViewController
case "giveUsMoney":
let weWantMoneyViewController = YourOtherViewController()
weWantMoneyViewController.user = user
destinationViewController = weWantMoneyViewController
default:
//loginFailed or some other status we don't know how to handle
destinationViewController = YourLoginViewController()
}
if let activeViewController = self._currentViewController,
type(of: activeViewController) !== type(of: destinationViewController) {
//we have an active viewController that is not the destination, cycle
self.cycleFromCurrentViewControllerToViewController(destinationViewController)
} else {
//no active viewControllers
self.displayContentController(destinationViewController)
}
}
//MARK: - Custom Content Controller Routing Methods
private func frameForContentController() -> CGRect {
return self.view.frame
}
private func newViewStartFrame() -> CGRect {
return CGRect(x: self.view.frame.origin.x,
y: self.view.frame.origin.y + self.view.frame.size.width,
width: self.view.frame.size.width,
height: self.view.frame.size.height)
}
private func oldViewEndFrame() -> CGRect {
return CGRect(x: self.view.frame.origin.x,
y: self.view.frame.origin.y - self.view.frame.size.width,
width: self.view.frame.size.width,
height: self.view.frame.size.height)
}
/**
Transitions viewControllers, adds-to/removes-from context, and animates views on/off screen.
*/
private func cycleFromCurrentViewControllerToViewController(_ newViewController: UIViewController) {
if let currentViewController = self._currentViewController {
self.cycleFromViewController(currentViewController, toViewController: newViewController)
}
}
private func cycleFromViewController(_ oldViewController:UIViewController, toViewController newViewController:UIViewController) {
let endFrame = self.oldViewEndFrame()
oldViewController.willMove(toParentViewController: nil)
self.addChildViewController(newViewController)
newViewController.view.frame = self.newViewStartFrame()
self.transition(from: oldViewController, to: newViewController,
duration: 0.5,
options: [],
animations: { () -> Void in
newViewController.view.frame = oldViewController.view.frame
oldViewController.view.frame = endFrame
}) { (finished:Bool) -> Void in
self.hideContentController(oldViewController)
self.displayContentController(newViewController)
}
}
/**
Adds a view controller to the hierarchy and displays its view
*/
private func displayContentController(_ contentController: UIViewController) {
self.addChildViewController(contentController)
contentController.view.frame = self.frameForContentController()
self._currentClientView = contentController.view
self.view.addSubview(self._currentClientView!)
self._currentViewController = contentController
contentController.didMove(toParentViewController: self)
}
/**
Removes a previously added view controller from the hierarchy
*/
private func hideContentController(_ contentController: UIViewController) {
contentController.willMove(toParentViewController: nil)
if (self._currentViewController == contentController) {
self._currentViewController = nil
}
contentController.view.removeFromSuperview()
contentController.removeFromParentViewController()
}
}