My application has tab bar with one of the tabs having a segmented control on navigation bar.
Based on segment clicked different view is displayed using a url.
I am calling the url in viewdidload method.I do not want to use viewwillAppear to call the url as it will be called each time the view is displayed.
I only want to call the url again whenever user closes the application and comes back.
Whats the best way to do this.Should I remove the view controller from and reload it again once the application is opened.
Please use a more descriptive title for your question next time!
There are notifications for this that you can observe in your application:
UIApplicationDidBecomeActiveNotification and UIApplicationWillEnterForegroundNotification come to mind.
Related
This is quite a common question, but after trying a lot to fix the issue, finally I have decided to post it on StackOverFlow.com
I have a tab bar based app. The tab bar is loaded in AppDelegate.m as follows:
self.tabBarController.viewControllers = #[viewController1, viewController2 , viewController3 , viewController4 , viewController5];
My 5th tab has a button for logout. When user clicks logout, I want to clear/reset entire app and go to login page which is a modalviewcontroller.
I have tried following while logging out:
NSMutableArray * vcs = [NSMutableArray
arrayWithArray:[self.tabBarController viewControllers]];
[vcs removeAllObjects ];//ObjectAtIndex:4];
[self.tabBarController setViewControllers:vcs];
This removes all views from tab-bar. But when I login again, nothing is displayed. I want to show my home screen, i.e. tab item 1 selected by default.
I have read that its not a good practice to call didFinishLaunchingWithOptions again manually.
Is there a way where I can reset all tab-bars and reinitialise them again ?
This will help me solving one more problem that is linked with this situation. When user logs out and log in again, and view controllers are not cleared, then logout page is shown again after login. And not the home view controller.
Please help.
Thanks in advance.
If you really want to start over, you should put a method, lets call it -(void)setupTabBarController, in the app delegate, and at start up you would call it from application:didFinishLaunchingWithOptions:. Later when you want to reset, call that method again from the login page. This method would have the creation of all the tab bar controller's view controllers in it, as well as setting the tab bar controller as the root view controller of the window.
However, it's not really clear that you need to do this, depending on what state all those controllers are in at logout time. Your problem with the logout page being shown again could probably be fixed in a simpler way.
Well, nothing is showing because you removed the views and never added them back in.
There is no need to remove the view controllers from the tab bar after you log out. You can just write a method to reset all the data in each view controller and then set the selected tab to what you desire.
I know, this is not really an answer to your question, but this could maybe help you too (and as I can't comment on post yet i have to post it like this :)).
I had some problems with "resetting" the navigation stack when the user logs out in my tabbar app too. In the beginning I had my tabbar-controller as the root controller and was displaying the login-screen modally but than it was quiet hard reset the navigation stack once the user loged out.
What I ended up doing and it works for me quiet well is, I set the login controller as root controller and after log in displayed the tab navigation modally. On log out I simply dismiss the tabbar-controller again - everything starts from the beginning again.
Maybe you could try this and see if it is easier to handle.
You should be add tabBar controller on second view controller. main view controller show home screen. when you navigate second view controller then you add tabBar here.
What I am asking may be impossible and sound weird, but here it goes.
Here is similar to what I want to achieve:
A user opens the app for the first time, there are two tab bars, in the first one (he has not tapped the second one yet) he presses a button that should initiate a progress view and text view changes and other view changes EVEN THOUGH the user has not loaded the other view controller by clicking the second tab bar.
So, is there a way to generally load a view controller before the user manually loads it himself, I know calling viewDidLoad manually will not help, any suggestions? Pretty confusing, it is like modifying a view but the controller has not loaded yet...
Thanks!
Make the changes in the other view controller and then let the controller configure its own view when it does its natural loading.
I'm developing a iPhone App, in which I'm changing the ViewController using presentModalViewController method upto 2/3 levels (e.g. Home-->Option-->Other-->More).
Now I want to get my app back to first screen or ViewController. If I use dismissModalViewControllerAnimated method, it just dismisses the current view controller only. But I want to clear the stack and start the Home screen again.
Thanks for any help.
Set the delegates properly for each level. So if you press Cancel or Done in More, it will call somehting like [other moreViewDidCancel] inside of which, you will call dismissModalViewController:Animated: and notify its parent view controller (delegate) that is should dismiss( so, [option otherViewDidCancel]) and so on till the top level.
I am developing an application which has 4 views and use navigation controller to navigate through. The first view is login interface. I just want to display login view when user press home button from second view. I have tried to use popToRootViewControllerAnimated in applicationDidEnterBackground. This does not work. Because I need to do this job only user press home button from second view (Second view contains MKMapView).
Can you please let me know what is the best option for this job? Basically I just need to check what view I am currently on.
Many Thanks
You could log a BOOL variable that the viewDidAppear function on your second controller sets to YES. And when you leave that view set it to NO. In applicationDidEnterForeground check it. If it is YES then the user left while in the second view.
i am having a UIWebView showing and HTML page that has some checkboxes, radio buttons. My Application has tabbar controller that switches b/w two controllers. How i can maintain the current state of UIWebView. ( e.g. i have selected a checkbox and i change the tab and go to other ViewController and again come back to UIWebView. the WebView resets itself and goes to the start... i want to maintain the state of UIWebView ( all the checkboxes clicked) .. how i will do that ??
any idea ??
thanks in advance
It sounds like you're loading your web view in viewDidAppear:, or some other method that gets called each time you switch to the tab. If you load your web view in viewDidLoad:, it will only get loaded once, and will retain its state when you switch tabs.
EDIT: When I wrote this answer back in 2009, I apparently didn't understand the view controller life cycle as well as I thought I did. Corey Floyd was right. The viewDidLoad: method can also get called multiple times, because UIViewController will unload its view in low memory situations if the view isn't being displayed. When the user switches back to the view, viewDidLoad gets called again to reconstruct the view.
How embarrassing.
I have an idea that might help:
to get the status from your app to the webpage, give the variables' values as request parameters with the called URL and let the webpage handle them and view the form elements accordingly.
to get the status from the webpage back to your app, let the webpage be refreshed each time any of its element is updated, and with the new URL give the new values of the changed elements. Back to your app, you can implement the UIWebViewDelegate and inside the method WebViewDidFinishLoad (or WebViewDidStartLoad as you prefer) use the webView.request.URL to parse the GET parameters and update your app accordingly.
hope this will help.