IOS ViewController navigation path - how to navigate back programatically - ios

I'm using IOS5 Storyboard. My View Controller path is as follows:
tabbarVC --> navigationVC-1 --> tableVC-1 --(via segue push)-> tableVC-2 --(via segue modal)-> navigationVC-2 --> tableVC-3
In the cancel button callback action method in tableVC-3 I call [self dismissViewControllerAnimated:YES completion:nil]; that successfully gets me back to tableVC-2. However when I try to examine the navigation path backwards in the debugger, I don't see a way to access tableVC-2 from navigationVC-2. I expected navigationVC-2 to maintain a link to tableVC-2 or navigationVC-1 but it doesn't seem to. Please see my debugger output below.
Can someone explain the navigation hierarchy and how to traverse the chain backwards programatically?
(gdb) po self
<tableVC-3: 0x6d33340>
(gdb) po (UIViewController*) [self navigationController]
<UINavigationController: 0x6d33560>
(gdb) po (UIViewController*)[[self navigationController] navigationController]
Can't print the description of a NIL object.
(gdb) po (UIViewController*)[[self navigationController] topViewController]
<tableVC-3: 0x6d33340>
(gdb) po (UIViewController*)[[self navigationController] presentingViewController]
<UITabBarController: 0x6b2eba0>
(gdb) po (UIViewController*)[[self navigationController] presentedViewController]
Can't print the description of a NIL object.
(gdb) po (UIViewController*)[[self navigationController] visibleViewController]
<tableVC-3: 0x6d33340>

This is an old question, but just to help anyone else who comes across this issue, there's a single command which'll make your life easier..
[self.navigationController popToRootViewControllerAnimated:TRUE];
Easy when you stumble across the right command, isn't it !
So, supposing you had a series of three screens in a Navigation Controller, and on the third screen you wanted the "Back" button to take you back to the initial screen.
-(void)viewDidLoad
{
[super viewDidLoad];
// change the back button and add an event handler
self.navigationItem.leftBarButtonItem =
[[UIBarButtonItem alloc] initWithTitle:#"Back"
style:UIBarButtonItemStyleBordered
target:self
action:#selector(handleBack:)];
}
-(void)handleBack:(id)sender
{
NSLog(#"About to go back to the first screen..");
[self.navigationController popToRootViewControllerAnimated:TRUE];
}

After some research using this and a couple other questions for modal UIViewControllers in storyboard to go back two views I used
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil];

Going throw an old response tough of updating it to be more complet.
To address this question :
Can someone explain the navigation hierarchy and how to traverse the chain backwards programatically?
The structure of your navigation :
tabbarVC --> navigationVC-1 --> tableVC-1 --(via segue push)-> tableVC-2 --(via segue modal)-> navigationVC-2 --> tableVC-3
Can be explain like this :
The TabbarVC is showing it's 'selectedViewController' (navigationVC-1).
NavigationVC-1 has its navigation stack compose of TableVC-1 and TableVC-2 (topViewController of NavigagtionVC-1)
Then NavigationVC-2 is presented Modally over the tabbarVC, so tabbarVC is the presentingViewController and NavigationVC-2 is the presentedViewController
So in order to reach tableVC-2 from tableVC-3 you would need to do something like this :
[(UINavigationController *)[(UITabBarController *)[tableVC-3 presentingViewController] selectedViewController] topViewController];
(don't do that in production code)
[tableVC-3 presentingViewController] as well as [tableVC-3.navigationController presentingViewController] will give you back the UITabBarController.
If you are using a UINavigationController you should use it's push and pop method to put UIViewController on or off the "presentation stack".
You will be able to access the UINavigationController from those UIViewController like this:
self.navigationController
If you want to go back more than one UIViewController on the "presentation stack" you can use this method on the UINavigationController
popToViewController:animated:
Pops view controllers until the specified view controller is at the top of the navigation stack.
- (NSArray *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated
To dismiss a UIViewController that was presented modally, the UIViewController that have presented it need to dismiss it with :
- (void)dismissModalViewControllerAnimated:(BOOL)animated
So in this case it should be :
[tableVC-2 dismissModalViewControllerAnimated:YES];

Swift
If you are using a navigation controller the you can navigate back to the previous view controller with
self.navigationController?.popViewControllerAnimated(true)
or back to the root view controller with
self.navigationController?.popToRootViewControllerAnimated(true)

Related

Dismiss Modal View Controller and Simultaneously Segue from Sending to Different View Controller in IOS

I launch a modal view controller VCM embedded in a Navigation controller from VC1.
The modal VC has a button to go to another View Controller, VC2.
if the user presses the button to go to VC2, I need to simultaneously dismiss the modal and also change the sending from VC1 to VC2. (It's important to dismiss the modal to get rid of it, so I don't have VCs accumulating on the stack.)
Here is the action method in the modal attached to the VC2 button.
- (IBAction)VC2ButtonPressed:(id)sender {
[self dismissViewControllerAnimated:true completion:nil];
//Above line works fine
[VC1 performSegueWithIdentifier:#"showVC2" sender:VC1];//No known class method error
}
I can dismiss the modal without any problem (first line) but can't figure out how to simultaneously segue to VC2. There is a storyboard segue in VC1 named 'showVC2' for what it's worth. I do not have any relevant class methods currently in the sending VC. Should I create a special class method? Or how can I invoke a method in the VC that launched the modal.
Edit:
I also tried:
[self.presentingViewController performSegueWithIdentifier:#"showVC2" sender:self];
This compiles but gives runtime error () has no segue with identifier 'showVC2''
I think this is because VC2 is embedded in a tabbarcontroller.
Edit2:
I tried putting code in completion handler as suggested by #Oscar but while code gets fired, VC2 does not load
[self dismissViewControllerAnimated:YES completion:^{
[self gotoVC2];
}];
new method
-(void)gotoVC2 {
LogDebug(#"gotoVC2 called");//DOES log to console
UIStoryboard *storyBoard = self.storyboard;
IDFeedVC *VC2 =
[storyBoard instantiateViewControllerWithIdentifier:#"vc2"];
[self presentViewController:VC2 animated:YES completion: nil];
}
Thanks for any ideas.

Build Hierarchy in Tabbarcontroller with Navigationcontroller

I have a Tabbarcontroller filled with 5 Viewcontrollers and Navigationcontrollers as I did here:
[self addChildViewController:VC1];
[self addChildViewController:NavigationController;
[self addChildViewController:VC2];
[self addChildViewController:VC3];
[self addChildViewController:VC4];
Now the thing is, that pressing a button on my Tabbar gets me to every ViewController easily, where I can present Xib-Files etc.
But now I want to have a Navigationcontroller, which is shown when pressing a button on my Tabbar. This Navigationcontroller itself has several Viewcontrollers.
I tried this to present my first Viewcontroller inside my Navigationcontroller (this code is from the Navigationcontroller.m):
- (void)viewDidLoad {
[super viewDidLoad];
[self addChildViewController:VC5];
[self presentViewController:VC5];
}
This expectedly did not work and gave me: Application tried to present modally an active controller.
Is there a good way to achieve such a specific goal? I'm struggling with this problem. Thanks in advance!
edit: This is how I set it up in my storyboard. In my programmatic approach the first view controller is not shown.
Instead of adding the VC5 view controller to the NavigationController as a child (unless it's meant to be a child?) add it as the root view controller when you add the NavigationController to the tab bar.
For example in your tab bar code:
[self addChildViewController:VC1];
UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:VC5];
[self addChildViewController:navigationController];
[self addChildViewController:VC2];
[self addChildViewController:VC3];
[self addChildViewController:VC4];
Apple docs on UINavigationController are here: https://developer.apple.com/library/ios/documentation/UIKit/Reference/UINavigationController_Class/#//apple_ref/occ/instm/UINavigationController/initWithRootViewController:

Pop THE RootViewController

I am developing an app that as first viewcontroller has an UIViewController.
This controller pushes a NavigationViewController that contains other controllers.
Now I need to pop the RootViewController of the NavigationController to go back to the initial UIViewController.
I tried with
[self dismissViewControllerAnimated:YES completion:nil];
and the app crashes("Tread1:EXC_BAD_ACCESS(code=1, address= ......)").
I tried with
[self.navigationController popViewControllerAnimated:YES];
and nothing happens.
The initial UIViewController calls
[self performSegueWithIdentifier:#"MyIdentifier" sender:self];
In the UIBuilder the segue is of type "Show(e.g. Push)"
Then I have a NavigationViewcontroller that contains the RootViewController and another Viewcontroller.
What I am trying to achieve is to go back to the first viewcontroller (the one outside the navigationcontroller) from the RootViewController. So I should have the navigationcontroller there.
What am I missing?
Apparently I had a couple of GestureRecognizer still in place that were causing the crash of the app.
The right method was:
[self dismissViewControllerAnimated:YES completion:nil];

Dismissing a ViewController lower in the stack does not behave as expected

I'm building a complex app that has kind of a branch in the middle.
At some point in the app, a particular UIViewController is presented, we'll call it mainViewController (shortened mainVC).
The mainVC presents another view controller, by code, using the following code (I strip out parts of it for privacy reasons):
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:#"SecondaryStoryboard" bundle:secondaryBundle];
SecondViewController *secondVC = [storyboard instantiateInitialViewController];
[self presentViewController:secondVC animated:YES completion:nil];
So the secondVC will later present another view controller, called thirdVC. This is done using a custom segue, set in the storyboard used in the code above, which code looks like this:
#implementation VCCustomPushSegue
- (void)perform {
UIView *sourceView = ((UIViewController *)self.sourceViewController).view;
UIView *destinationView = ((UIViewController *)self.destinationViewController).view;
UIWindow *window = [[[UIApplication sharedApplication] delegate] window];
destinationView.center = CGPointMake(sourceView.center.x + sourceView.frame.size.width, destinationView.center.y);
[window insertSubview:destinationView aboveSubview:sourceView];
[UIView animateWithDuration:0.4
animations:^{
destinationView.center = CGPointMake(sourceView.center.x, destinationView.center.y);
sourceView.center = CGPointMake(0 - sourceView.center.x, destinationView.center.y);
}
completion:^(BOOL finished){
[self.sourceViewController presentViewController:self.destinationViewController animated:NO completion:nil];
}];
}
#end
As you can see this segue presents the destination view controller modally (by the use of presentViewController:) with a custom animation (a slide from right to left).
So basically up to here everything is fine. I present the secondVC with a classic modal animation (slide up from bottom) and present the thirdVC with my custom transition.
But when I want to dismiss the thirdVC, what I want is to go back directly to the mainVC. So I call the following from the thirdVC :
self.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:_animate completion:nil];
That way, I'm calling dismissViewControllerAnimated: directly on mainVC (referenced by self.presentingViewController.presentingViewController), and I'm expecting the thirdVC to be dismissed with an animation, and the secondVC to just disappear without animation.
As Apple says in the UIViewController Class Documentation:
The presenting view controller is responsible for dismissing the view
controller it presented. If you call this method on the presented view
controller itself, it automatically forwards the message to the
presenting view controller.
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.
When this happens, only the top-most view is dismissed in an animated
fashion; any intermediate view controllers are simply removed from the
stack. The top-most view is dismissed using its modal transition
style, which may differ from the styles used by other view controllers
lower in the stack.
The issue is that it's not what happens. In my scenario, the thirdVC disappears, and shows the secondVC being dismissed with the classic modal slide to bottom animation.
What am I doing wrong ?
Edit :
So #codeFi's answer is probably working in a classic project, but the problem here is that I'm working on a framework. So mainVC would be in a client app, and the secondVC and thirdVC are in my framework, in a separate storyboard. I don't have access to mainVC in any other way than a reference to it in my code, so unwind segues are unfortunately not an option here.
I've been having this exact same issue, and I've managed to visually work around it by adding a snapshot of the screen as a subview to secondVC.view, like so:
if (self.presentedViewController.presentedViewController) {
[self.presentedViewController.view addSubview:[[UIScreen mainScreen] snapshotViewAfterScreenUpdates:NO]];
}
[self dismissViewControllerAnimated:YES completion:nil];
Not pretty, but it seems to be working.
NOTE: if your secondVC has a navigation bar, you will need to hide the navigation bar in between snapshotting the screen and adding the snapshot as a subview to secondVC, as otherwise the snapshot will appear below the navigation bar, thus seemingly displaying a double navigation bar during the dismissal animation. Code:
if (self.presentedViewController.presentedViewController) {
UIView *snapshot = [[UIScreen mainScreen] snapshotViewAfterScreenUpdates:NO];
[self.presentedViewController.navigationController setNavigationBarHidden:YES animated:NO];
[self.presentedViewController.view addSubview:snapshot];
}
[self dismissViewControllerAnimated:YES completion:nil];
I had the same issue and I've fixed it by using UnwindSegues.
Basically, all you have to do is add an IBAction Unwind Segue method in the ViewController that you want to segue to and then connect in IB the Exit action to your Unwind Segue method.
Example:
Let's say you have three ViewControllers (VC1, VC2, VC3) and you want to go from VC3 to VC1.
Step 1
Add a method to VC1 like the following:
- (IBAction)unwindToVC1:(UIStoryboardSegue*)sender
{
}
Step 2
Go in Interface Builder to VC3 and select it. Then CTRL-drag from your VC icon to Exit icon and select the method you've just added in VC1.
Step 3
While still in IB and with VC3 selected, select your Unwind Segue and in the Attributes Inspector add a Segue Identifier.
Step 4
Go to VC3 where you need to perform your segue (or dismiss the VC) and add the following:
[self performSegueWithIdentifier:#"VC1Segue" sender:self];

How to switch between view controllers and get rid of the previous one

In android, switching between activities, is fairly straightforward
you call
Intent intent = new Intent(this,NextActivity.class); <- define the next activity
startActivity(intent); <- start the next activity
finish(); < -get rid of the current activity
now in iOS i know how to do this:
UIViewController *nextviewcontroller = [[UIViewController alloc]initWithNibName:#"nextvc" bundle:nil];
[self presentViewcontroller:nextviewcontroller animated:YES completion:nil];
How do I get rid of the current view controller? so that currentviewcontroller dies after presenting nextviewcontroller ?
[self dismissViewController:YES]; doesnt seem to do the trick
the lifecycle methods viewWillDisappear and viewDidDisappear are called even if I don't call [self dismissViewController:YES];
i want "currentviewcontroller" to be removed from the memory, and from the viewcontroller stack, so that clicking "back" in "nextviewcontroller" will go to some thirdviewcontroller that was before currentviewcontroller
In iOS is different, since there's no concept of Activity and everything is more focused on the app itself (in Android you can mix activities from different apps). Therefore, there's no concept of "view controller stack".
The most similar concept is the "navigation stack" of navigation controllers, where you actually push and pop new view controller into some kind of linear navigation. A navigation bar is automatically created and populated with back buttons.
presentViewController will show your view controller modally upon the current one, but you can't thrash the presenting one since it's holding and containing ("defining context") the new one.
If you use a navigation controller for your navigation hierarchy (I don't know if you can), you can override the back button and use something like
UIViewController * prev = self.navigationController.viewControllers[self.navigationController.viewControllers.count -2 ]
[self.navigationController popToViewController:prev animated:YES]
With a modal view controller, you may try something like (I haven't tried but it may work)
[self.presentingViewController.navigationController popViewControllerAnimated:YES]
You should write one of these code into the target action of your close button.
iOS doesn't maintain a global stack of controllers in the way that Android does. Each app shows a controller at its root, and that one is responsible for showing the other controllers in the app. Controllers can display other controllers modally using presentViewcontroller:animated:completion: but the presenting controller remains underneath the presented one.
If your current controller is the root controller, then instead of using presentViewcontroller:animated:completion: you'd just do this:
self.view.window.rootViewController = nextViewController;
It's very common for the root controller to be a UINavigationController, which does manage a stack of controllers. If that is the case, and if your current controller is at the top of the stack, you'd do this:
[self.navigationController popViewControllerAnimated:NO];
[self.navigationController pushViewController:nextViewController animated:YES];
If your setup is different, you'd do something different; it's hard to say what without knowing more. But it's most likely that you'd be in the UINavigationController case.
In the viewDidAppear of your nextviewcontroller you could add :
-(void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
NSArray *controllers = self.navigationController.viewControllers;
NSMutableArray *newViewControllers = [NSMutableArray arrayWithArray:controllers];
[newViewControllers removeObjectAtIndex:[controllers count]-2];
self.navigationController.viewControllers = newViewControllers;
}
There is nothing available like this in iOS but you can achieve it doing something like below
NSArray *viewControllers=[self.navigationController viewControllers];
NSMutableArray *newControllers=[[NSMutableArray alloc] init];
for(int i=[viewControllers indexOfObject:self];i<viewControllers.count;i++){
[newControllers addObject:[viewControllers objectAtIndex:i]];
}
[self.navigationController setViewControllers:[[NSArray alloc] initWithArray:newControllers]];
I have tried the method of storing all the view controllers in an array but it didn't work for me . When you try popViewController it will move to the View Controller which is last in the stack.
You can make 2 navigation controllers and switch between them and also switch between the view controllers of a particular Navigation Controller.
For eg.
You can switch between 2 Navigation Controller using the following code:
FirstNavController *fisrtView=[storyboard instantiateViewControllerWithIdentifier:#"firstnavcontroller"];
self.window.rootViewController = firstView;
}else{
SecondNavController *secondView=[storyboard instantiateViewControllerWithIdentifier:#"loginnavcontroller"];
self.window.rootViewController = secondView;
}
If your FirstNavController has 2 ViewControllers then you can switch between them using pushViewController
SecondViewController *sc = [self.storyboard instantiateViewControllerWithIdentifier:#"secondviewcontroller"];
[[self navigationController] pushViewController:sc animated:YES];
and popViewController
[self.navigationController popViewControllerAnimated:YES];

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