Adding login screen in front of Cocoa Touch Tab Bar Application for IOS

In your AppDelegate, at the end of the application didFinishLaunchingWithOptions method you'll see this:

[window addSubview:tabcontroller.view];[window makeKeyAndVisible];return YES;

Simply initialize your login view controller and add it after the tabcontroller, like this:

initialScreenViewController = [[InitialScreenViewController alloc] init];[window addSubview:tabcontroller.view];[window addSubview:initialScreenViewController.view];[window makeKeyAndVisible];return YES;

In you login viewcontroller, after authenticating the user you can hide it like this:

[self.parentViewController.view setHidden:YES];

which allows you to show it again if you have a logout feature.

The standard way is the following:

• Package everything related to login screen into a view and a UIViewController subclass which manages that.

• Present that view modally in the app delegate in application:didFinishLaunchingWithOptions: by calling

  LoginController*loginController= ... ; // create the view controller for the login screen[self.tabController presentModalViewController:loginController animated:YES];

This way, the animation between the transition etc. is automatically handled.

You can later dismiss it after you successfully logs in. It can be done from inside the LoginController by

[self.parentViewController dismissModalViewControllerAnimated:YES];

However, I often need to do additional setup once the logging-in is done. So, I would first tell the app delegate that the login is done, and then perform

[self.tabController dismissModalViewControllerAnimated:YES];

from the app delegate. Then I can perform additional tasks there.

To communicate back to the app delegate, I would use NSNotification, but that might be a bit difficult for you.

One way which might be easier to understand (but uglier to my taste) is to define a method, say loginDone in the app delegate.Then, inside the LoginViewController, you can do

MyAppDelegate*appDelegate=[[UIApplication sharedApplication] delegate];[appDelegate loginDone];

If you are starting with the default tab bar application you can do it like this:

• In the MainWindow.xib, create a UIView that contains all the stuff you want to have on your password screen
• Hook whatever you need up to IBOutlets in the AppDelegate, and write the method that checks if the password is valid.
• In the applicationDidFinishLaunching method, replace [window addSubview:tabBarController.view]; with [window addSubview:/*whatever you called the view with the password stuff in it*/];
• If the user enters the correct password do this:

[passView removeFromSuperview];[window addSubview:tabBarController.view];

And you should be in the regular tab bar application.