I have a problem with the UINavigationController. It about a client or serverside logout.
The idea for serverside logout is this, every 15 seconds a function is called that checks if the App is still logged in. If that is not the case then jump to the LoginViewController.
The Logout can also happen from the App itself. It executs simular code.
There are three relevant Controllers, LoginViewController is where we want to end up, SignOutController is where the 'Sign out'-Button is located and MainViewController.
Here are the relevant code parts.
First, the UINavigationController gets allcated like this:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
splashScreenViewController_ = [[SplashScreenViewController alloc] initWithNibName:#"SplashScreenViewController" bundle:nil];
uiNav_ = [[UINavigationController alloc] initWithRootViewController:splashScreenViewController_];
uiNav_.navigationBar.barStyle = UIBarStyleBlackTranslucent;
uiNav_.navigationBarHidden = YES;
[window_ setRootViewController:uiNav_];
[window_ makeKeyAndVisible];
return YES;
}
When the 'Sign out'-Button is pressed or the App figures out that the Server has forced a logout, this code is executed (same code, diffrent functions):
LoginViewController *loginView = [[LoginViewController alloc]initWithNibName:#"LoginViewController" bundle:nil];
[self.navigationController pushViewController:loginView animated:YES];
[loginView release];
If its a Serverside Logout it just reloads the MainViewController, every 15 seconds you see the animation of MainViewController sliding in. Its goes in a cycle from there, every 15 seconds it reloads.
If you click the 'Sign out'-Button it jumps to MainViewController instead of LoginViewController and starts the same cycle discribed above.
P.S. I have checked if any importend variable is nil, and I have checked that initalisation code is actually executed.
Edit: I think I did not mention that. My app works 99% of the time. Just one in a while this happen that the Sign-out button does not work and I start this cycle. Normally it works fine.
For the 15 second cycle where a new LoginViewController slides in it just seems you are not stopping to check if the app is logged in after realizing it wasn't. You should have some sort of boolean to store that and cancel the timer or whatever you use.
I don't understand what you say happens when you press the logout button, but I don't think you are making a good user interface.
I suggest you start the application by adding to the navigation controller the loginViewController as root. Then you add without animation the one you want to start with (for example MainViewController). Whenever the application is logged out of the service you pop the view controllers until the first one, which sould be the login one.
You have the method popToRootViewControllerAnimated: for that.
If you want to preserve the splash screen you can set it as the root view controller of the app, and chenge it to the uiNavigationController when you have finished loading.
The timer won't stop automatically just because you've pushed a view on top of another. It will be there until the controller it started on is released, which will only happen after it has been removed from the stack.
Also, you don't need to push MainViewController onto the stack after every check, you'll end up with multiple instances of it, each on top of another.
Also, without really knowing much about the architecture of the app, it would seem like a good idea to make LoginViewController modal, they really can't do anything if they've not logged in right? A modally presented viewcontroller wouldn't be affected by the navigation stack, and would also retain the users navigation stack much easier than having to manually push/pop controllers.
Related
I have a Login View where user enters username and password which is working fine to call the next view. Now when the user clicks logout, I am calling the Login viewController using following:
loginViewController *login = [[loginViewController alloc] initWithNibName:#"loginViewController" bundle:nil];
[self presentModalViewController:login animated:YES];
I don't know whether allocation the view again again on logout button action is a good idea.
I am using ARC but I dont know calling the loginViewController will push all the allocated memory of previous viewControllers.
PS:
loginViewController is the root view controler -ie- it is called right after the appDelegate.
I have tried popViewController method of the navigationController but it is not working.
Any other suggestion would be really grateful
As you are using ARC, the objects are managed by the iOS, so once you dismiss the loginViewController it will no longer available in memory. So you for next time you need to allocate & present the loginView again, your code is fine, works good..
I have a sample app made using tabBar with login & logout transitions. Here you can change your rootViewController as per your requirement.
What is the right way to change XIB View which loaded at app start depending on some app settings. Of course I know how to get all settings I need.
In your application's delegate, in the method
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
if(yourSettings)
myViewController = [[MyViewController alloc] initWithNibName:#"FirstNibName" bundle:nil];
else
myViewController = [[MyViewController alloc] initWithNibName:#"SecondNibName" bundle:nil];
self.window.rootViewController = self.myViewController;
[self.window makeKeyAndVisible];
return YES;
}
And that's it. Probably you may want to save your settings in your user defaults so you can load the view properly.
However, I would use 2 different view controllers, as you probably want them to do different things, not just modify some graphics.
EDIT-
Let me see if I understand. You will always load the first view controller and, if some conditions are met, you modally want to present the second view controller that will get dismissed at some point, returning the user to the first view controller. If this is the case, I suggest you move the code in your first view controller, in viewDidLoad or better yet in viewDidAppear, as this view controller will always get loaded. Also this way the user can see that he will eventually go to that view controller. I use something like this in applications the user needs to login to so that it will be obvious for him that he cannot continue until he does login.
I can't say that this is the right way to do it, because it's up to the programmer how he arranges his code, but it would seem to me that the place that controls what view and how it appears belongs in a view controller and not in the delegate, especially considering that your first view controller always gets loaded. It should be up to that view controller to see if it presents the second one or not.
I think this is a pretty common usecase as I have seen it in several apps. But after spending couple of days, I am still struggling with this. I have a structure like the following:
UITabBarController
-- UINavigationController1
---- UITableViewController1
-- UINavigationController2
---- UITableViewController2
Now I have a logout button on UITableViewController2. When I click on that logout button I want all and any viewcontroller to be deallocated, all view unloaded. Basically start fresh like launching the app. I basically want the viewDidLoad on each of those UITableViewController called again.
I tried the following method to be called in my appdelegate when the logout action on UITableViewController2 is taken.
-(void) logout {
for (UINavigationController* ctrl in self.tabBarController.viewControllers) {
[ctrl popToRootViewControllerAnimated:NO];
ctrl.visibleViewController.view = nil;
}
[self.tabBarController.view removeFromSuperview];
[self.window addSubview:self.tabBarController.view];
}
But alas, it does not seem to work?
Any ideas how such a thing is accomplished? Also I see different behaviors in iOS4 vs iOS5 with the visibleViewController. I am not using any modal viewcontroller here. Any gotchas?
Update: I am not using ARC
thanks
mbh
Your for-loop will release and thus dealloc any view controllers that you have pushed onto the respective UINavigationController roots (depending on how many tabs you have), i.e. as these will not have a superview when you pop back to the root of each navigation controller, these are dealloc-ed automatically. These are your UITableViewControllers taken care of.
As for the respective UINavigationControllers, you would need your tabbar-controller to release the old instance. IMHO, this should be done for you when you release the UITabBarController.
This then leaves the UITabBarController itself. I don't think it can be done tbh. Your code will only remove the view, but not dealloc the tabbar controller itself. And as Krishna K points out, you need at least one view controller to reload all others.
Putting the code into the appdelegate makes sense, but you need to ensure that your logout() will not cause a retain on the UITableViewController2 as well as the UITabbarController as it's called from UITableViewController2 somewhere.
One idea to explore, does your AppDelegate hold an instance to the TabBar-Controller which you could release and create a new instance after removing the view from self.window?
// manually create UITabBarController - AppDelegate holds instance
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
mytabcontroller=[[UITabBarController alloc] initWithNibName:#"foo" bundle:nil];
}
- (void) logout {
[self.tabBarController.view removeFromSuperview];
[mytabcontroller release];
mytabcontroller=[[UITabBarController alloc] initWithNibName:#"foo" bundle:nil];
[self.window addSubview:self.tabBarController.view];
}
But as I said, there might be caveats with memory management at this point.
You need to release your view controllers. When their release method is called, that method should include statements to release all of its object's resources (and also dealloc its superclass).
Your rootViewController for both Navigation controllers are their respective TableView controllers. So I don't think popToRootViewController would do anything.
You probably need to reset the data and refresh the views instead of deallocating the views.
I will like my application that always starts as the first time I open it. I have several view controllers and when I exit my application and I open it again I see the view controller where I left of. Maybe I have to call the method applicationWillTerminate method.
I use this code to open a new view:
UIViewController *control = [[SomeViewController alloc] initWithNibName:#"SomeViewController"
bundle:nil];
UINavigationController *navControl = [[UINavigationController alloc]
initWithRootViewController:control];
[self presentModalViewController:navControl animated:NO];
[navControl setNavigationBarHidden:YES];
[control release];
[navControl release];
this code works great when linking it to buttons. But when I place that code in the applicationDidBecomeActive method it does not work.
The easiest way is to set UIApplicationExitsOnSuspend in Info.plist.
That really isn't the expected behaviour, though. Users expect to see the app "where they left off", especially if they've only briefly left the app (e.g. because they got a phone call).
Your code snippet adds a view controller, but is unlikely to work since your app delegate is not a UIViewController. It also doesn't do anything about removing the old view controllers.
EDIT: If all you need to do is display a splash screen (or something), then it's something like this:
In -applicationDidEnterBackground:, add a "splash screen" view (not a view controller) to self.window. (iOS takes a "screenshot" after you return from -applicationDidEnterBackground: and uses this in the app-switch animation; you want this to be what the user sees when switching back to your app)
In -applicationWillEnterForeground:, do whatever animations you want and eventually remove the view from the window (call -removeFromSuperview).
EDIT 2: The same will work in -applicationWillResignActive:/-applicationWillBecomeActive:, except this happens on a sleep/wake event, which might not be what you want...
I'd avoid using view controllers for this, because trying to shoehorn a view controller in the view controller hierarchy is likely to be problematic (for example, you have to figure out which VC to present it from, and you have to do the "right thing" if the user backgrounds your app while the VC is on screen, and...)
The reason it doesn't work in applicationDidBecomeActive is that method is only sent to the Application delegate, which doesn't know about presentModalViewController.
I suggest instead that in your appDelegate, implement applicationWillEnterForeground:, which should restore the state to a newly launched application (equivalent to what the state is at the end of application:didFinishLaunchingWithOptions: ).
OR...(edits)
If you just want a certain viewController to run (which is still loaded, right?)...For example, if you have a tab controller and just want to go to the root of the first view controller, put the following code into applicationWillEnterForeground:
UITabBarController * myTabBar = self.tabBarController;
myTabBar.selectedIndex = 0;
[[myTabBar.viewControllers objectAtIndex:0] popToRootViewControllerAnimated:NO];
Temporary solution:
I made my application crash on applicationWillResignActive method and it works. My application needs to run an animation when I launch it. But this works because next time the application runs it starts like the first time I opened it.
I have a UIViewController in which it should pop up a LoginViewController if a user is not yet login. The question is where should I call this:
LoginViewController* lvc = [[LoginViewController alloc] init];
lvc.delegate = self;
//[lvc setModalPresentationStyle:UIModalPresentationFullScreen];
[self presentModalViewController:lvc animated:NO];
[lvc release];
should it be in the viewDidLoad or in the viewWillAppear? I guess it makes sense to put it in the viewWillAppear? I tried to put it inside the viewDidLoad and it gives me an extra border to the left and right of the view. Why is this?
UPDATE:
What I am trying to do here is to call presentModalViewController on the DetailViewController of a UISplitViewApplication. However nothing happens when I do so. I tried creating a new fresh project of a UISplitViewApplication and still it didn't work.
The question is why? and how do I present a modal view in the viewWillAppear of a UISplitViewApplication
The modal window tries to initialize itself with respect to the view controller that called it (resizing the nib, for example). Creating and displaying it in its parent's viewDidLoad can sometimes give it wrong information since the parent is still itself loading. This is why you are seeing discrepancies. Presenting the modal controller in viewDidAppear is better in this case since all the parameters are ready to pass to the modal controller so it can load its own view properly. Though sometimes if you have a lot to load, even that isn't enough and you will need to wait longer before you can present your modal view (which doesn't sound like your case at all, so there should be nothing to worry about there). I hope this helps, though
I would place something like this in the AppDelegate.
- (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions
{
[self.window addSubview:self.viewController.view];
[self.window makeKeyAndVisible];
// Show the login screen if the user hasn't logged in yet
if (... login check here...)
{
LoginViewController* loginController = [[LoginViewController alloc] init];
[self.viewController presentModalViewController:loginController animated:NO];
[loginController release];
}
}
Your login screen will be placed on top of your normal viewcontroller. After a succesfull login dismiss the LoginViewController and your user can start using your app.