Here's the scenario: if this is a user's first time logging into my web service, I present a modal login view. Upon success, the user may have multiple items in his/her account and must choose one of them before he/she can proceed with the rest of the app.
I want to put up another modal view with a picker so the user can make the choice.
All the examples I've seen of multiple modals presented are canned ones (like the email composer modal, with the people picker modal coming up over it), which is of no use because the code isn't available.
When I try putting up the login modal, then dismissing it, then presenting the picker, I get a recursion somewhere with a selector being sent to subviews being sent to subviews being sent to ....
Can anyone point me to some sample code?
I'm keeping a reference to the login view, so I figured I'd just pose the stack (well, two) modal views, then dismiss the login modal and they'd all go away (like the documentation says), but I can't seem to get this going.
Thanks in advance.
I have found that I could do this, but had to eliminate animation on the first dismiss, iff I was using animation on the 2nd presentModalViewController
ContactsViewController* controller = [[ContactsViewController alloc] ...
UINavigationController* navigationController = [[UINavigationController alloc] initWithRootViewController:controller];
[self.navigationController presentModalViewController:navigationController animated:YES];
[controller release], controller = nil;
and then in my delegate method that is being called from the initial modal view
[self.navigationController dismissModalViewControllerAnimated:NO]; // dismiss without animation
[self.navigationController presentModalViewController:anotherViewController animated:YES];
This behavior was observed on OS 3.0.1.
Related
I have an app that has an initial login screen then when the user wants to sign up, they are presented with a registration form that is three view controllers presented modally. When the user completes the form on the third screen (by pressing a "Done" button), I want the user to be taken back to the initial login screen.
I have tried doing this in the third view controller:
[self dismissViewControllerAnimated:NO completion:nil]
[self.presentingViewController dismissViewControllerAnimated:NO completion:nil]
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:NO completion:nil]
However it only dismissed two of the view controllers and not all 3. Why did this happen?
As other people pointed out, there are more elegant/efficient/easier ways to achieve similar results from the UX perspective: via a navigation controller, or a page view controller, or other container.
Short/quick answer: you need to go one step further in the chain of presenting view controllers, because the dismissal request needs to be sent to the controller that's presenting, and not to the one that's being presented. And you can send the dismiss request to that controller only, it will take care of popping from the stack the child controllers.
UIViewController *ctrl = self.presentingViewController.presentingViewController.presentingViewController;
[ctrl dismissViewControllerAnimated:NO completion:nil]
To explain why, and hopefully help other people better understand the controller presenting logic in iOS, below you can find are more details.
Let's start from Apple documentation on dismissViewControllerAnimated:completion:
Dismisses the view controller that was presented modally by the view controller.
The presenting view controller is responsible for dismissing the view controller it presented. If you call this method on the presented view controller itself, UIKit asks the presenting view controller to handle the dismissal.
Thus [self dismissViewControllerAnimated:NO completion:nil] simply forwarded the request to self.presentingViewController. Which means the first two lines had the same effect (actually the 2nd line did nothing as there was no presented controller after the 1st one executed).
This is why your dismissal of view controllers worked only the top 2 ones. You should've start with self.presentingViewController and go along the chain of presenting view controllers. But this is not very elegant and can cause problems if later on the hierarchy of view controllers changes.
Continuing to read on the documentation, we stumble upon this:
If you present several view controllers in succession, thus building a stack of presented view controllers, calling this method on a view controller lower in the stack dismisses its immediate child view controller and all view controllers above that child on the stack.
So you needn't call dismissViewControllerAnimated:completion: three times, a call on the controller that you want to come back will suffice. At this point, passing a reference to that controller would be more reliable than navigating through the stack of view controllers.
There are some more useful details in the documentation, for example regarding what transitions apply when dismissing multiple controllers at once.
I recommend you go through the whole documentation, not only for this method, but for all methods/classes that you use in your application. You'll likely discover things that will make your life easier.
And if you don't have the time to read all Apple's documentation on UIKit, you can read it when you run into problems, like in this case with dismissViewControllerAnimated:completion: not working as you thought it would.
As a closing note, there are some more subtle issues with your approach, as the actual dismissal takes place in another runloop cycle, as it's possible to generate console warnings and not behave as expected. This is why further actions regarding presenting/dismissing other controllers should be done in the completion block, to give a change to UIKit to finish updating its internal state.
Totally understood. What I will do is embed a navigation controller instead of using modal. I have a case just like you. I have LoginViewController to be the root view controller of the UINavigationController. SignupViewController will be presented by push method. For ResetPasswordViewController, I will use modal because it's supposed to go back to LoginViewController no matter the results. Then, you can dismiss the whole UINavigationController from SignupViewController or LoginViewController.
Second approach will be like, you come up with your own mechanism to reference the presented UIViewController via a shared instance. Then, you can easily dismiss it. Be careful with the memory management. After dismissing it, you should consider whether you need to nil it right away.
I know three ways to dismiss several viewControllers:
Use a chain of completion blocks
~
UIViewController *theVC = self.presentingViewController;
UIViewController *theOtherVC = theVC.presentingViewController;
[self dismissViewControllerAnimated:NO
completion:^
{
[theVC dismissViewControllerAnimated:NO
completion:^
{
[theOtherVC dismissViewControllerAnimated:NO completion:nil];
}];
}];
Use 'viewWillAppear:' method of viewControllers
~
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
if (self.shouldDismiss)
{
CustomVC *theVC = (id)self.presentingViewController;
theVC.shouldDismiss = YES;
[self dismissViewControllerAnimated:NO completion:nil];
}
}
Pass a reference to LoginVC1 further down the chain.
(This is the best approach so far)
Imagine you have some StandardVC, which presented LoginVC1.
Then, LoginVC1 presented LoginVC2.
Then, LoginVC2 presented LoginVC3.
An easy way of doing what you want would be to call (from inside your LoginVC3.m file)
[myLoginVC1 dismissViewControllerAnimated:YES completion:nil];
In this case your LoginVC1 would lose its strong reference (from StandardVC), which means that both LoginVC2 and LoginVC3 would also be deallocated.
So, all you need to do is let your LoginVC3 know that LoginVC1 exists.
If you don't want to pass a reference of LoginVC1, you can use:
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:NO completion:nil];
However, the above approaches are NOT the correct ways of doing what you want to do.
I would recommend you doing the following:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
if (!self.isUserLoggedIn)
{
[UIApplication sharedApplication].keyWindow.rootViewController = self.myLoginVC;
}
return YES;
}
Then, when user finished his login process, you can use
[UIApplication sharedApplication].keyWindow.rootViewController = self.myUsualStartVC;
I can't find the correct method on how to reload a modal view controller from within itself. I'm developing a very simple UI based app but I'm not sure how to do this.
I open the modal view with the following:
MainView *mainmview = [[MainView alloc] initWithNibName:#"submod" bundle:nil];
mainmview.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self mainmview animated:YES];
and then can dismiss it depending on iOS version. However this has no effect when used on what i need to be a simple restart button. Any help is appreciated.
You will have to implement your own "refresh" functionality - define a "refresh" method inside the modal view controller's class and do whatever needs to be done inside it - if for instance you have a tableview that requires a reload or to refresh your views depending on new data, etc...
I have an app that is controled through a UITabBar. In one of the sections within the tab bar, I have a navigation table. It works fine from an example I did from one of the books but I want to be able to go another view controller (aka another xib file) when the user selects a row and I want the user to be able to go back easily. I realize this has to do with pushingViewControllers but I am stuck. Here is where I think the problem is. my code is at the bottom. If you notice, I commented out
// [self presentModalViewController:flowerDetailViewController animated:YES];
While this did take me to the my flowerDetailViewController XIB file, I lost the ability to do navigation (go back). If anyone has any ideas or suggestions, it would be much appreciated.
Thank you
-(void)tableView:(UITableView *)tableView
didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
FlowerDetailViewController *flowerDetailViewController =
[[FlowerDetailViewController alloc] initWithNibName:
#"FlowerDetailViewController" bundle:nil];
/*flowerDetailViewController.detailURL=
[[NSURL alloc] initWithString:
[[[flowerData objectAtIndex:indexPath.section] objectAtIndex:
indexPath.row] objectForKey:#"url"]];*/
flowerDetailViewController.title=
[[[flowerData objectAtIndex:indexPath.section] objectAtIndex:
indexPath.row] objectForKey:#"name"];
//[self presentModalViewController:flowerDetailViewController animated:YES];
[self.navigationController pushViewController:
flowerDetailViewController animated:YES];
[flowerDetailViewController release];
}
It doesn't make any sense to execute these two methods on the same view consecutively.
[self presentModalViewController:flowerDetailViewController animated:YES];
..
[self.navigationController pushViewController: flowerDetailViewController animated:YES];
because they give a very different result, from user experience point of view.
The first one presents a view modaly. Modaly means, that he application brings up the view to the top (imagine a Z-axis, when you hold the phone, it is a line from the phone to you, on top of it means closer to you), and the user is stuck in that view exclusively because it is on the top, he/she cannot touch anything else from the application unless he resolves the options presented in the view and the view goes away.
The second method is pushing the view onto he stack of views that all belong to the navigation controller. The navigation controller pushes views onto the screen like you would lay a stack of cards onto the table, card1, put onto that card 2, put onto that card 3...and so on card N. But you still have the ability to touch other options that are all around the navigation controller.To get back to the card 1, you need to remove card(views) that are on top of it, for removing on-top views, the navigation controller provides the back button automatically.
Only you cann tell, which of these two is handy in terms of your application UI and design.
I'm implementing a Passcode feature in my iPhone app which has a UITabBarController as a root view controller. I have everything working great in most situations, by displaying a modal Passcode ViewController from the tabBarController when the app goes into the background, like so:
- (void)applicationDidEnterBackground:(UIApplication *)application
{
if ([[NSUserDefaults standardUserDefaults] valueForKey:kPasscodeStringKey]) {
PasscodeEntryVC *passcodeView = [[PasscodeEntryVC alloc] init];
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:passcodeView];
[tabBarController presentModalViewController:nav animated:NO];
}
}
My problem comes when the app is already displaying a modal view controller when it enters the background. Then, no passcode view appears. What would be the correct way to do this? Instead of just sending the message to the tabBarController to present the view, should I be checking first to see what the current view is, then have that present the passcode? If so, how is this done? Thanks.
First - you are leaking memory because you do not release your passcodeView and navigation controller nav.
Second - you could keep a simple BOOL variable that is updated whenever a modal view is presented or dismissed. If there is a modal view, just call dismissModalViewController:animated: in your applicationDidEnterBackground: method.
You could also check the frontmost view controller with [self.navigationController.topViewController class], but I have found this to be unreliable.
What I usually do is to ensure that any views I have that may present a modal view controller to dismiss the modal view controller whenever it is sent the UIApplicationWillResignActiveNotification notification, while over in my app delegate, I set it up exactly like yours.
One caveat though, is that whenever you dismiss the said modal view controllers, you need to ensure that you dismiss them with animated: set to NO before presenting your passcode view controller.
i am designing an app that has a login screen. it is a UIView with username/password and a button to submit. once the user authenticated successfully, i want to load a new xib file that holds a navigation controller and a navigation bar. below the bar i want to load a tableView and switch between other views as i move along with the programming of it.
what i did is create a new class that inherits from UINavigationController and assembled the xib file to include the navigation controller. i hooked it back up to file's owner and i'm loading the navigation controller modally like this:
myNavController* navVC = [[myNavController alloc] initWithNibName:#"navXibFile" bundle:nil];
[self presentModalViewController:navVC animated:YES];
[navVC release];
this works okay as the navigation controller shows up. however, it shows up with no title, even though i've set one up in IB. moreover, the tableView's delegates are hooked up via IB but i cannot even see empty lines. all i see is an empty navigation bar at the top and blank view (one piece) below it.
thank you for your help.
so i figured it out... first it's a design decision right? is the app being managed by a navigation controller? if so (which is my case), expect the main (first) view, that is a login page, all you need to do is to hide the navigation bar in your ViewdidLoad for the main view:
[self.navigationController setNavigationBarHidden:YES animated:YES];
once the user logs in and you push the next view like this:
MainTableViewController* mainTableVC = [[MainTableViewController alloc]
initWithNibName:#"MainTableViewController" bundle:nil];
[self.navigationController pushViewController:mainTableVC animated:YES];
[mainTableVC release];
and lastly, in the ViewDidLoad of the next view controller:
[self.navigationController setNavigationBarHidden:NO animated:YES];
in case your app needs a navigation controller for a specific section of the app but not all if it, you will need to use the VC to manage this, in a similar way the appDelegate manages the sample navigation based sample app.
i hope this helps anyone struggling with wrapping their minds around the design patterns implemented here.
cheers.