UIView Login screen to tabbar logic - objective-c

Question

Folks,
I'm having trouble with some navigation logic. Currently I have a simple two tabbed tabbar application. But I want to show a loginscreen in front. So that would be an UIView.
Currently the code is as follows:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
UIViewController *viewController1 = [[roosterViewController alloc] initWithNibName:#"roosterViewController" bundle:nil];
UIViewController *viewController2 = [[SecondViewController alloc] initWithNibName:#"SecondViewController" bundle:nil];
self.tabBarController = [[UITabBarController alloc] init];
self.tabBarController.viewControllers = #[viewController1, viewController2];
self.window.rootViewController = self.tabBarController;
[self.window makeKeyAndVisible];
return YES;
}
So this pushes a simple tabcontroller. Well, now I want to have a login screen. So that would be a simple UIView which pushes the tabbar controller. But I can't seem to see the logic on how to do this.
I've been trying to present a modal view controller, but the thing is: the tabbar will be loaded on the background. Since I need the username/password information to work on the tabbarview, this won't work.
My Logic would be:
delegate > load loginViewController > load tabbar controller
But, then I need to be able to "logout". So I need to destroy the tabbar controller and present the login screen.
Any thoughts on this?

Answer 1

You could do something like this:
You could create a protocol which your AppDelegate conforms to.
#protocol Authenticator <NSObject>
#required
- (void)authenticateWithUsername:(NSString *)username andPassword:(NSString *)password;
- (bool)authenticated;
#optional
- (void)authenticationSuccess;
- (void)authenticationFailure;
...
#interface AppDelegate : UIResponder <UIApplication, Authenticator>
#property (readonly, nonatomic, assign) bool loggedIn;
...
#implementation AppDelegate
#synthesize loggedIn = _loggedIn;
- (void)authenticateWithUsername:(NSString *)username andPassword:(NSString *)password
{
//if success
_loggedIn = YES;
//check if app responds to the optional authenticateSuccess method
//call it if it does
//else fail
//do stuff
}
- (bool)authenticated
{
if (_loggedIn != NULL) {
return _loggedIn;
}
//do other stuff
}
...
I am a bit fuzzy on proper objective-c conventions and syntax so forgive me if I have a few errors, but anyways that is some logic and pseudo-code to work off of. Tweak that to your needs.
I hope this helps.
EDIT:
I guess my answer was a bit unfinished. It seemed to to me the answer to your question was strongly connected to some kind of authentication structure. If your app is so closely connected to authentication, then why not control its flow through the authentication structure. I guess that was my point, and since all this would be conveniently and readily available in your apps delegate, you could call these methods anywhere you wanted, therefore letting your authentication logic decide which view controller to show for example.

Answer 2

As mentioned have the login as the rootView and if the login is successful enable the other tabbarButtons else don't enable them like this..initially set the bool to false on view load then if successful enable a tabbar button else don't.
login = TRUE;
UITabBarItem *reportit = [[[[self tabBarController]tabBar]items] objectAtIndex:2];
[reportit setEnabled:TRUE];
else {
UITabBarItem *reportit = [[[[self tabBarController]tabBar]items] objectAtIndex:2];
[reportit setEnabled:FALSE];
}

Answer 3

I recommend you set the login screen as root. When the login is successful, you simply change the root of the window to the tabbar controller, with a nice animation.

Answer 4

I would recommend that you set up the tab bar just like you have it right now, but immediately following the makeKeyAndVisible you instantiate and present the login view controller, without animation.
This way once the app has launched the user does not see the tabBarController, but only the modally presented login screen. Once login is done you simply dismiss the login view controller and beneath it appears .... drumroll the tabbarcontroller!

Answer 5

Expanding on Levi's answer, this is how you switch the root view controller continuously (with an animation). Just add this extension:
extension UIViewController
{
func transitionToRootViewController(viewController:UIViewController)
{
UIView.transitionWithView(self.view.window,
duration: 0.3,
options: UIViewAnimationOptions.TransitionCrossDissolve,
animations: {
window.rootViewController = viewController
},
completion: nil
)
}
}
...to the UIViewController class (that will make the method transitionToRootViewController () available to all your view controllers), and call it on the exiting view controller, passing the entering view controller (that you perhaps instantiated form a separate storybord, who knows...) as a parameter.
(The basic idea was taken from here. I simplified the code a bit)
Beware though: I tried this code to insert a tab bar controller, whose selected index (tab) contained a navigation controller. During the transition animation, the navigation controller's navigation bar "underlaps" the status bar (carrier, clock, battery level), and only after the transition animation completes, it "jumps" into its place immediately, creating a horribly distracting (and unpolished) effect.
I fixed it by adding the following code to the child view controller embedded in the navigation controller:
override func viewWillAppear(animated: Bool)
{
super.viewWillAppear(animated)
self.navigationController?.navigationBar.layer.removeAllAnimations()
// ^ THIS
}
(This fix was taken from this forum.)
I haven't checked, but the same issue might occur whenever you transition into a navigation controller (or any plain-vanilla UIViewController that happens to have a navigation bar attached), whether it is embedded in a tab bar controller or not.