How to check user confidencial in a tab based application?

Question

I am building a tab based iphone application, all the information in each tab is user related, which means the user have to login before go to each tab. I put the username/password inputs in the first tab, and I will store the user confidencial in key chain after a successful login. However what's the best way to check it before the user enter the other tabs? and prevent the unauthorized user to enter the other tabs except login tab? I don't want to do this verification in every view controllers.

+1 for using the keychain for user credentials. – Till Mar 31 '12 at 18:50 — Till, Mar 31 '12 at 18:50

score 1 · Answer 1 · answered Mar 31 '12 at 14:05

1

You can use method in Singleton class (like in app delegate). In every tab you can check whether user is login like

if(appdelegate.userLogine) { // User is login show view

}else { // Post Notification

}

answered Mar 31 '12 at 14:05

Mangesh

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Thanks, but is there a centre place to do this check instead of invoking the checking logic in every tab controllers? – scottliyq Mar 31 '12 at 15:17

Till · Accepted Answer · 2012-04-01T10:34:45.483

That could be done using the UITabBarControllerDelegate.

Implement it e.g. within your UIApplication delegate and assign it to your UITabBarController.

AppDelegate Header:

@interface AppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate>
{
    //[...]
}
//[...]
@end

AppDelegate Implementation:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    //[...]

    //instanciate and configure your tabbarcontroller
    //[...]

    //assign this instance as the delegate of our tabbarcontroller
    tabBarController.delegate = self;
}

The following method gets called whenever the user selects any tab. Returning NO means the selection should not actually happen. You could, for example, in that situation show an alert asking the user to login first.

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
    //is the user logged in and did the user select any but the first tab?
    if (!userLoggedIn &&
        [tabBarController.viewControllers indexOfObject:viewController] != 0)
    {   //nope->...
        //force the user to the first tab
        tabBarController.selectedIndex = 0;
        //prevent the originally chosen tab selection
        return NO;
    }
    //user is logged in, it is safe to select the chosen tab
    return YES;
}

Thanks, one more question, once the validation fails, can I force the user to go to the first tab? — scottliyq, Apr 01 '12 at 04:49

How to check user confidencial in a tab based application?

2 Answers2