I'm currently working on an iPhone app.
This app has a login screen, also a signup screen.
After the user has successfully signed up, I dismiss the signup view, then the app automatically logs in using the created account. After which, the login view is dismissed, showing the main view.
I'm trying to modify this by immediately dismissing the login view, since I already have the account details of the user when the signup is successful. Basically, the ideal flow is: after the user successfully signs up, I save the username and password in a singleton class, then dismiss the signup view. When I get to the parent view (which is the login screen), I have a variable that checks if there was a successful signup. If that variable is true, I want to immediately dismiss the login view.
However, I come across this error message: Data Formatters temporarily unavailable, will re-try after a 'continue'. (Unknown error loading shared library "/Developer/usr/lib/libXcodeDebuggerSupport.dylib")
I'm not really sure why this happens. I have no problems dismissing the login view when I go through the actual login procedure - which of course also dismisses the login view if the user inputs a correct username and password.
I'm not exactly sure, but I'm starting to think that the iPhone cannot handle dismissing 2 view controllers almost at the same time.
Is it possible that I'm dismissing the login view too quickly? Is that a factor? Is there anyway for me to be able to dismiss 2 view controllers almost simultaneously without coming across this error message?
It seems likely that dismissing 2 UIViewControllers at the same time is the cause of this error (I have seen it for various other reasons, including running short of memory).
Try a different flow, where you check for the saved values first, then load your main view if valid, or the login view if not. I do this in one app, and it works fine.
Related
I have been all over stackoverflow and all over Google and I cannot seem to figure this one out. Here's my scenario:
I have my app's "main screen" where the user first makes decisions about what they're going to do. The app works off of a CoreData database which is created by "importing" XML files. The user can choose to open an XML file attached to an email in my application, which automatically triggers my main screen to show up and run the import of the file.
I can get this far without any issues. In my storyboard, I have a segue called ParseSegue from my main screen to a view controller which will handle the parsing and give the user some status information.
When the main screen is called via the email app, the main screen automatically calls
[self performSegueWithIdentifier:#"ParseSegue" sender:self];
I then check for this segue name in prepareForSegue and it's a valid name. This is where I assign the file URL to the parser controller so that it can parse the correct file.
The problem is that the segue never actually happens. The prepareForSegue method gets called, the name "ParseSegue" can be checked against and is valid, but the segue itself simply does not happen. If I add a button to the main screen and tell it to perform the segue within the storyboard, it works fine. But calling it programmatically seems to do nothing.
It turns out that I was looking in the wrong place entirely. My problem was that in my appDelegate, where the app reacts to the incoming URL, I was inadvertently creating a new instance of my storyboard and my main view controller. This was different than the one which was already active and may or may not have been on the screen.
The controller I was creating was never actually shown. I only noticed this because the log:
NSLog(#"Source: %#", [segue.sourceViewController description]);
would show different memory addresses for my test (the button push) and the import test. This led me to believe that I was, in fact, working with two different instances of the storyboard and the app's main view controller. Thanks to Paul for the suggestion of logging the destination and the source controllers.
I have been searching the net, and i have found many very good examples on how to create a login page for your iPhone app. However... none of then meets my demands, an since i am new to iPhone development( i know java / c / C++ and objective-c), so the programming itself is not the issue.. The issue is where to put the code and what design patterns to use..
My app is a basic tabbar controller with 3 tabs that could contain navigation controllers, but that is not important.. it is the part before the tabbar controller i am interrested in, namely the need to authenticate the user towards a Lotus Domino Server. I have the authenification code working, so that is not the issue either..
By the way, i am concentrating on IOS5 and using storyboards..
Where do i put the "check if user is still authenticated" code ? The domino server will log the user out after 1 hour, so if the user has the app open(in background) then the code that downloads data will die if the user is not told that the session has expired..
So here is what i would like..
When the app launches, show the login page. This is working for now with the Login View Controller as initial controller, and a modal segue to the tabbar controller..
Next time the App is launched(either from background or from new is user has closed it completely), check if username and password is stored in userdefaults, and then just login in background, and if that fails(password has changed or another failure) then show the login view controller again..
So to sum up, where do i put the "part 2" code ? I have a seperate authenticator class that is using delegates, and i can use this class to perform the authentification, and the it will answer back if all is good.
Do i put this in the AppDelegate code ? If i put it in one of the tabbar viewcontrollers, then there might be an issue with the user having tab2 open when launching after 2 hours, and if the check is in tab1, then tab 2 will fail.. Should i put the code in ALL the tabbar viewcontrollers ? Naaa, that is ugly..
I am leaning towards the AppDelegate(appdidbecomeactive), but can that be used as delegate in my authenticator class ?
That was a bit long, sorry for that, but i needed to explain my problem fully so people would understand what i need..
Thank you for your help.. This is my first post, but this forum is fantastic :)
I'd definitely put both part one and part two code in the AppDelegate.
This allows you to create the appropriate viewcontroller at app start and remove the tabbarcontroller from within the AppDelegate if the authentication times out etc.
I'm not sure about your modal segue to a tabbarcontroller though (I'm not familiar with storyboards yet though). Modal implies you wouldn't be able to present any other view modally on top of the tabbar controller. I think it sounds like it would be much more appropriate to create your logincontroller and tabbarcontroller programmatically and add/remove them directly in your application’s main window as needed from your AppDelegate.
I would tell the AppDelegate to check the login status very time the tab is changed or data loaded.
In my app there is authentication required, so when you launch one of the tabs on tab bar, "class A" checks are there credentials saved if not, "class B" modal view controller with fields to login launches.
So my question is : in which method in class A (loadView, viewWillAppear or maybe in another one) should be implemented checking if there are credentials saved and other stuff described above.
And my additional second question is:
is pushing modalviewcontroller correct way to show login screen, or i should do that differently?
Thank you for reply guys.
OH ! One More Thinh
And one more thing. I've done implementing LoginView by adding delegate and presenting ModalVC (Harkonian the Piquant's method). But in my tab bar app i have got very confusing problem. I mean when user taps login button (assume that everything was correct and he's able to secured data) how PROPERLY switch to tab where is secured info. I mean previously selected tab.
i did it by adding in
-(IBAction) login {
//some code
self.tabBarController.selectedIndex =1;
And it seem to work good but is it correct ?
I have a very similar use case in my app -- it requires a passcode to authenticate. After a lot of testing and tweaking I found the following design to be the best approach:
Don't use class A to launch your credentials VC -- use the app delegate instead.
For security purposes, typically you'll want the credentials VC to show before the user can view the underlying view. It's much easier to handle this in the app delegate than in a VC. In addition, you need to consider what happens when your app is backgrounded -- a screen shot is taken of the current state of the app. If you are using viewController A to show the credentials view, when the app relaunches the user will be able to see whatever sensitive information was visible on app close until the app finishes launching and VC A presents the credentials VC.
Don't insert your credentials view into an existing ViewController -- use a new UIWindow instead.
You don't ever want any other view to be able to sit on top of your credentials view. Ever. Even views that would normally always be on top, like UIAlertView. The easiest way to achieve this is to have a special UIWindow just for your credentials view. Show this window and hide the primary app window whenever you need to display the credentials view.
How does this approach look in practice?
If you are at all interested in how well this design works, you can check out the passcode feature in Audiotorium Notes for iPad. I spent a lot of time with this design to make sure it was as secure as possible.
If you have any specific implementation quests feel free to ask and I'll try to answer them.
I'm new in world of iphone programming. I try to make simple login application. My goal is to have 2 different view controllers. When app start login screen should appear. This screen contains two Text fields and one button(login). I want when user press login button to send his username and password to remote server through http and if they are legal to load tab bar controller with two bars. In first bar user should see his id and in second to see his mail. Is it possible this and can you give some direction?
Best regards,
Nikolay
Yes this is possible.
After entering the account details user will press the login button. On that event you can send the account details to the remote server using NSURLConnection. After authenticating details in the server. Server should send a response with the status of sucess/failure in an XML. You can catch the response and parse the message using a XML parser example:NSXMLParser. If the message is success then call the method to show the TabController. If message is failure then show some alert.
You will be in need of some class like NSURLConnection for server communication. And NSXMLParser for parsing data. You can check sample apps of this classes for better understanding and their implementation. Good Luck.
I Guess the answer you want is how to lad the views in a odered way... if so, you must first load the tabbar. on the viewDidload from your first view controller, load the login view controller in a modal way, using delegate to return to the main view after the login...
loading a view controller modally:
[self PresentModalViewController:yourController];
In developing my current iPhone application, I'm having issues handling the login, logout functionality of presenting views.
I'd like to have my application have the following flow, but I cannot seem to figure out the proper viewcontroller setup:
When a user is not logged in, a login screen is immediately presented. Upon a successful login, the main application is displayed. The main application is a TabBarController. When returning back to the application, if you have already logged in, the login window will not display, but immediately go into the main tab bar. Once in the app, you can "logout" and it will take you back to the login scren.
Please let me know if I need to go into further detail. There are a few other questions on here that are similar but not exactly what I'm looking for.
Thanks!
I would consider two ways of doing this:
have the login screen be a modal view controller that pops over the main UI.
e.g.
if (currentCredentials == nil) [self presentModalViewController:loginView animated:YES];
or alternately, handle switching between views using your app delegate.