Does presentModalViewController: add the view controller to the stack? - objective-c

I have a main navigation controller with a root view controller. In the root view controller, on the push of a button I present second view controller like this:
SecondVC *secondVC = [[SecondVC alloc] initWithNibName:#"SecondVC" bundle:nil];
[self.navigationController presentModalViewController:secondVC animated:YES];
In the second view controller, on the push of an other button, I want to present a third view controller (this time from a Storyboard):
ThirdVC *thirdVC = [[UIStoryboard storyboardWithName:#"Settings" bundle:nil] instantiateInitialViewController];
[self.navigationController presentModalViewController:thirdVC animated:YES];
However this doesn't do anything. I debugged and it turned out, that self.navigationController is nil.
Shouldn't it be the main navigation controller? Or doesn't presentModalViewController: add the view controller to the stack? Do I always have to put a view controller in a navigation controller before presenting id modally?

The new view controller SecondVC is being presented modally, and it's not added to the view controller stack of the navigationController. You need to create a new UINavigationController, and put SecondVC inside the navController before presenting it modally.

You'll need to add something like:
UINavigationController *navControl = [[UINavigationController alloc] initWithRootViewController:secondVC];
[self addChildViewController:navController];
[self.navigationController presentModalViewController:secondVC animated:<#(BOOL)#>]

your view controller while being presented is not inside a navigation controller. And will not have access to the presenting controllers navigation controller.
Furthermore if you push or pop stack items on the navigation controller beneath the modal view controller you will likely not notice anything.
If you want to put the controller in the stack you can alternatively show the view controller yourself.
[self.view addSubView:myViewController.view]
myViewController.view.frame = self.view.bounds;
and to dismiss the view controller you would simply remove it from its superview.
the drawback here is that some of the did and will appear methods are not called on the view controller. Therefore you may want to call them yourself.
But the principal is much the same. And you can easily simulate the presenting animation with the animation system.
Give it a starting point below your form, then start your animation block and put the view.frame to superview.bounds also giving it an animation time. I find that 2 seconds is ok. sometimes less.
at this point the presented view is inside the controller which is on the stack. Now while you cant directly modify the navigation controller within the presented view controller you could set a delegate that tells the original your intentions and therefore the presenting view controller (the one on the navigation stack) can push or pop the view controllers as requested. And the presented view controller will be pushed along with it.
Another positive point is that you can do much like other apps do, and present a semi modal view. With a partially transparent background. this way you can show things happening behind the view even tho they dont directly manipulate it.

Related

What is best approach to add back button for first view controller in navigation controller?

I'm beginner iOS developer, so don't know how to solve my problem correctly. I have one navigation controller and want to make modal transition to another navigation controller that will have back button on it's first view controller.
In my first navigation controller I made this:
InfoViewController *destinatinViewController = [[InfoViewController alloc] initWithNibName:#"InfoViewController" bundle:nil];
[self presentViewController:destinatinViewController animated:YES completion:nil];
InfoViewController is UINavigationViewController.
Then I made this in InfoViewController (second navigation controller):
InfoRootViewController *rootViewController = [[InfoRootViewController alloc] initWithNibName:#"InfoRootViewController" bundle:nil];
[self pushViewController:rootViewController animated:NO];
For now I know how to add button to go back, but it has not styling (certainly arrow). As I understand because it is only one view in stack of second navigation controller.
So, I need your help to add styled back button for first view controller of navigation controller, because I don't want to make own styling (I'm lazy).
Thanks, for any advance!
PS: I made modal transition because, it has animations like from bottom or top. I tried to use custom animations for pushViewController, but in iOS 7 they're working not correctly.
I'll let someone else help you with the back button issue because I think it's a mistake to create one for a modal view controller that's presented from the bottom of the screen. Typically, such a modal view controller is dismissed with a cancel button or its equivalent. If you really think that you need a back button then you should probably push the view controller onto the existing navigation stack instead of presenting it modally.
However, I am happy to show you how to properly alloc/init a navigation controller and then present it.
I don't know why you're subclassing UINavigationController, but I'm going to pretend that you don't need to (which is probably the case).
InfoRootViewController *rootViewController = [[InfoRootViewController alloc] initWithNibName:#"InfoRootViewController" bundle:nil];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
[self presentViewController:navController animated:YES completion:nil];

Load view with the navigation controller?

I have an app where my main view is embedded in a navigation controller. From there, buttons push onto other view controllers. This all works fine. However, one of the view controllers it pushes to updates one of the root's values and presents it again. However this time, it only presents the ViewController without the navigation controller, and of course, pressing the button to go back will end in a crash. Hopefully this picture will help understand my issue. The pressing enter thing isn't really a big deal, I just call this function on return of the keyboard.
Code to go back to the main controller:
-(void)createNewMain:(NSString*)newAddress {
ViewController* newController = [self.storyboard instantiateViewControllerWithIdentifier:#"MainView"];
newController.labelText = newAddress;
newController.connected = self.connected;
[self presentViewController:newController animated:YES completion:nil];
}
The problem is simple, you're presenting the instantiated view controller modally.
Replace
[self presentViewController:newController animated:YES completion:nil];
with
[self.navigationController pushViewController:newController animated:yes];
Also, you can make a segue to do that from the storyboard. When the segue executes, it will create a new instance and will not use the previously created one.
Note: If you really don't need to create a new instance, consider using delegation to exchange information between objects.
You don't really want to "return" to a new instance of a root controller. What you need to do to properly return to the root controller is to pop all the other ones from the navigation controller's stack like this:
[self.navigationController popToRootViewControllerAnimated:YES];
Use Delegation to pass the expected/required message you want from your Pi Controller to your Root View Controller and set it up according to the message. You don't need to create a new instance of your Root View Controller from there. You can always go back to your root view controller from anywhere in the navigation stack by using
[[self navigationController] popToRootViewControllerAnimated:YES];

NSNotificationCenter for presenting multiple modals?

I have an app delegate, whose default view should be preceeded by a modal view controller, and sometimes by two modal view controllers. So in the app delegate's didFinishLaunchingWithOptions, I'm checking if there is need for, and in that case displays, the first modal view controller.
Upon dismissing the first modal view controller (using [self dismissModalViewControllerAnimated:YES];), I may want to display the second modal view controller. This is known by the app delegate as well.
So my solution was to use NSNotificationCenter to tell the app delegate that the first modal view controller now have been dismissed. When that happens, the second modal view controller can be displayed by the app delegate, if it is needed.
It works fine, but is there a cleaner solution? I think NSNotificationCenter is really ugly stuff.
Note on displaying multiple modal view controllers at once
I did try to display the first AND the second modal view controller inside of didFinishLaunchingWithOptions, but I never got it working. Here's what I tried:
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
[window setRootViewController:tabBarController];
[self.window makeKeyAndVisible];
[tabBarController presentModalViewController:pinViewController animated:NO];
if([self needsActivation]) {
[tabBarController presentModalViewController:activationViewController
animated:YES];
}
}
UPDATE: The above code works with the following correction:
if([self needsActivation]) {
[pinViewController presentModalViewController:activationViewController
animated:YES];
}
In this particular case, there was no need for NSNotificationCenter, as I thought. I had tried to display multiple modal view controllers, but I'd made an error.
When displaying the modal view controller B from the modal view controller A, it works fine. I had tried presenting modal view controller A and B from a parent view controller.
So when presenting modal view controllers in a hierarchy instead, there is no need for NSNotificationCenter. The view controllers are dismissing themselves, animations works and I'm a step further towards bending the UIKit to my will.
I've edited the code in my question, which now works fine.

loading a UINavigation controller from a UIView

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.

Navigation controller problem

I have a normal view controller and I want to add a uinavigationcontroller to it so:
[self.view addSubview:aNavigationController.view];
everything works, fine, aNavigationController is an IBOutlet, in the XIB, it's view controller is loaded from another xib, then in the navigation controller's view controller's class I type this:
- (IBAction)anAction {
[self.navigationController pushViewController:aViewController animated:YES];
}
everything works fine, the view changes to the aViewController view and it's animated, but when I type in aViewController's class this:
- (IBAction)anotherAction {
[self.navigationController popViewControllerAnimated:YES];
}
it crashes, why?
Because there is no view to pop. When you're trying to pop view controller it is expected that there is some view in stack, i.e. the view from which you calling popViewControllerAnimated was already pushed earlier.
So popping is not just awesome animation but navigation through stack of views in navigation controller. In this particular situation you're trying to call -1st element of this stack, that is the reason of the crash.
Dig deeper here:
http://developer.apple.com/library/ios/#featuredarticles/ViewControllerPGforiPhoneOS/NavigationControllers/NavigationControllers.html#//apple_ref/doc/uid/TP40007457-CH103-SW1