I have a NavigationController that the following VC's are embedded in: VC1 -> VC2 -> VC3 -> VC4 -> VC5. My problem is that when I segue from VC5 (after editing is completed), I send you back to VC3, but I want to programmatically throw VC4 and VC5 off the stack, i.e. when the user is sent back to VC3, I want "back" in the navagitionBar to take you to VC2 (and not VC5 where you really came from).
This comes up a lot in IOS, where you want to edit the model, then send them back to the tableView/Collection view, but since editing is done, you don't want the editing viewControllers in the navigation stack anymore as its too confusing of UX.
In the screenshot below, the VC on the top right is VC5: which is segued back to the PinViewController (VC3) via self.performSegueWithIdentifier("backToPins", sender: self)
How can I do this?
don't use segue to come back (pop).
you should use popToViewController and pass specific viewcontroller as argument to pop that viewcontroller.
for example if you want to go on 3rd view controller out of five then you can do something like below. you can just change index from viewcontroller array to go different view controller.
let viewControllers: [UIViewController] = self.navigationController!.viewControllers as [UIViewController];
self.navigationController!.popToViewController(viewControllers[viewControllers.count - 3], animated: true);
If you are using segue that means you add (push) new viewcontroller to navigation stack. in your example your stack after reaching 5th view is like,
VC1 - VC2 - VC3 - VC4 - VC5 (top of stack)
now if you performsegue to go back to VC3 then stack should be like this,
VC1 - VC2 - VC3 - VC4 - VC5 - VC3(top of stack)
and if you pop to VC3 then your stack is like,
VC1 - VC2 - VC3 (top of stack).
so pop viewcintrollers to go back don't use segue
hope this will help :)
The best way to do this is via an unwind segue.
In VC3 you define an appropriate unwind function:
#IBAction func unwind(segue:UIStoryboardSegue) {
if let sourceViewController = segue.sourceViewController as? VC5 {
let myNewData=sourceViewController.someProperty
self.someFunctionThatUpdatesScene()
}
Then in the VC5 scene you can create an unwind segue in one of two ways.
If you want it to be triggered directly from an object, such as a UIButton, you drag from the action in the inspector to the exit icon at the top of the scene and select unwind from the pop up.
If you want to trigger the unwind programatically then you drag from the view controller object in the explorer on the left to the exit icon and select unwind from the popup. You will now see an unwind segue in the explorer and you can give it an identifier like you would with any segue. You can use this identifier with performSegueWithIdentifier
The advantage of this approach is that you don't need to make any assumptions about the depth of UINavigationController stack and you don't need to implement a delegate/protocol to pass data back.
Apple has a very good Tech Note on Using Unwind Segues
Related
I'm studying the tutorial from Apple Developer: Start Developing iOS Apps (Swift), and I'm confused with push and modal segue.
There are two scenarios, Save and Cancel button in navigation bar, backing to scene 1 from scene 2.
If the Cancel button is pressed, it will call different method for dismissing scene 2:
#IBAction func cancel(_ sender: UIBarButtonItem) {
// Depending on style of presentation (modal or push presentation), this view controller needs to be dismissed in two different ways.
let isPresentingInAddMealMode = presentingViewController is UINavigationController
if isPresentingInAddMealMode {
dismiss(animated: true, completion: nil)
}
else if let owningNavigationController = navigationController{
owningNavigationController.popViewController(animated: true)
}
else {
fatalError("The MealViewController is not inside a navigation controller.")
}
}
In this method, if the scene is presented by modal segue, dismiss(animated:completion:) is called, and
if the scene is presented by push segue, popViewController(animated:) is called for poping up the ViewController from the navigation stack.
But for the Save button, the tutorial overrides a method in scene 2, prepare(for:sender:), and a action method in scene 1, unwindToMealList(sender:).
And it drag the Save button to Exit (the button in the scene dock) and choose unWindToMealList(sender:) method.
So the flow will be: prepare(for:sender:) -> scene 2 dismissed and scene 1 presented -> unWindToMealList(sender:)
I'm wondering that the code snippets didn't dismiss explictly scene 2 and remove the ViewController in navigation stack when Save button is pressed.
I know that modal segue won't push ViewController to navigation stack, but push segue will push it.
Why the code snippets doesn't pop up it from navigation stack?
Many thanks.
It seems like the tutorial you are reading is making use of unwind segues.
Unwind segues, just like normal segues, have a source and a destination and you can prepare for it in prepareForSegue, but instead of presenting the destination VC, it will dismiss the source VC so that the destination VC is shown.
Unwind segues behave differently in different situations. When you present VC B from VC A using a push segue, and an unwind segue from B to A, the unwind segue will pop VC B from the navigation stack. When you present VC B from VC A modally, the unwind segue will dismiss the modally presented VC.
As you can see, unwind segues are quite smart. It will decide for itself what to do in order to show the destination VC. It can even pop two or more VCs in the navigation stack!
When presenting or dismissing VC, I do not want to keep hiding and showing tabBar because it creates a poor user experience. Instead, I want present the next VC straight over the tab bar such that when I dismiss the nextVC by dragging slowly from left to right, I can see the tabBar hidden behind the view (As shown in image below)
Note, my app has two tabs with two VCs(VCA,VCB) associated to it. Both VC also have navigation bar embedded. VCA segues to VCA1 and VCB segues to VCB1. At the moment, inside VCA and VCB I am calling the following function to segue with some hiding and unhiding done when viewWillappear (Code below).
self.navigationController?.showViewController(vc, sender: self)
// Inside ViewWillAppear Only reappear the tab bar if we successfully enter Discover VC (To prevent drag back half way causing tab bar to cause comment entry to be floating). This code check if we have successfully enters DiscoverVC
if let tc = transitionCoordinator() {
if tc.initiallyInteractive() == true {
tc.notifyWhenInteractionEndsUsingBlock({(context: UIViewControllerTransitionCoordinatorContext) -> Void in
if context.isCancelled() {
// do nothing!
}
else {
// not cancelled, do it
self.tabbarController.tabBar.hidden = false
}
})
} else {
// not interactive, do it
self.tabbarController.tabBar.hidden = false
}
} else {
// not interactive, do it
self.tabbarController.tabBar.hidden = false
}
----------Working solution from GOKUL-----------
Gokul's answer is close to spot on. I have played with his solution and came up with the following improvement to eliminate the need to have a redundant VC and also eliminate the initial VC being shown for a brief second before tabVC appears. But without Gokul, I would never ever come up with this!!
Additionally, Gokul's method would create a bug for me because even though I do have a initial "normal" VC as LoginVC before tabVC is shown. This loginVC is ONLY the rootVC if the user needs to login. So by setting the rootVC to tabVC in most cases, the navVC will never be registered.
The solution is to embed navigation controller and tabBar controller to one VC. But it ONLY works if the navVC is before the TabBarVC. I am not sure why but the only way that allowed me to have navVC-> tabVC-> VC1/VC2 is to embed VC1 with a navVC first than click on VC1 again to embed tabVC (It wouldn't allow me to insert one before tabVC and I also had to click the VC1 again after embedding the NavVC).
For your requirement we need to make some small changes in your given view hierarchy
Let me explain step by step,
To meet your requirement we have to add a UIViewController(let's say InitialVC) embedded with a UINavigationController and make it as initial viewcontroller.
Then add a UITabbarController with 2 VC (VCA,VCB) // IMPORTANT: Without any navigationcontroller embedded.
Add a segue between InitalVC and TabbarController with an unique identifier(ex: Initial)
In viewWillAppear of InitalVC perform segue as below (InitialVC is unnecessary to our design we are using this just to bridge navigationController and tabbarController).
self.performSegueWithIdentifier("Initial", sender: nil)
In TabbarControllerclass hide your back button, this ensures that InitialVC is unreachable.
override func viewDidLoad() {
super.viewDidLoad()
self.navigationItem.hidesBackButton = true
}
Now add a segue from a button between VCA and VCA1, thats it build and run you will see VCA1 presenting over VCA's tabbar.
What we have changed?
Instead of adding UINavigationController inside UITabbarController we have done vice versa. We can't directly add Tabbar inside navigation to do that we are using InitialVC between them.
Result:
1st way is create a image of the tabbar using UIGraphicsGetImageFromCurrentImageContext and set it on the bottom of the other view...
2nd way is show the next view in another new window that is above the tabbar, that way you wont need to hide the tabbar anymore, but seems like its in the navigation controller so this way doesnt seems available
Hiding and unhiding the tab bar is unnecessary. You only need to embed the UITabBarController inside the UINavigationController. That is, UINavigationController as the initial vc, UITabBarController as the root vc of UINavigationController.
My hierarchy
UINavigationController -> UIViewController
-> UITabViewController
-> ViewController1
-> ViewController2
-> ViewController3
I want to navigate back from
ViewController1 -> UIViewController.
Anyone know please solve this issues.
"Unwind" is your answer.
Create an IBAction method to unwind segue. Define this method in a controller in which you want to unwind (Controller from you want to jump back to main controller).
- (IBAction) prepareForUnwind:(UIStoryboardSegue *)segue {
}
Now connect back button (in this case "Home" button) with this method in Storyboard. To connect unwind action -> Ctrl-drag to "Exit" outlet button of your controller.
Note: If you are using Xcode version less than 6.0 than "Exit" outlet is located at bottom of your view controller.
This will navigate back to your root navigation controller. That is UIViewController.
For further separation you can give an identifier to unwind segue and make different actions for exit to last controller.
Select identifier from left list and give an identifier in Attributes inspector.
Key points:
Write unwind method in a controller which will be exited.
Connection to "Exit" delegate will only works after you define unwind method.
Ctrl+Drag from a control to the Exit symbol to select the unwind segue you want this control to perform
Unwind segues appear below the Exit symbol for each connection made
You can give those unwind segues an identifier to have different activities performed.
You can use
[navigationController popToViewController:<#(UIViewController *)#> animated:<#(BOOL)#>];
just provide the instance of the viewController you want to pop to and set animated property to YES if u want pop with animation and NO if not.
Here the controller UIViewController is the rootViewController of UINavigationController. So you just need to pop to the rootViewController from the ViewController1
[self.navigationController popToRootViewControllerAnimated:YES];
You can done by this:
ViewController *loginVC = [self.storyboard instantiateViewControllerWithIdentifier:#"ViewController"];
[self.navigationController popToViewController: loginVC animated:YES]
My use case as follows:
VC1 - Root Controller
VC2 & VC3 are different view controllers
VC1 is delegate of VC2
VC1 presents VC2
Then as delegated, VC1 dismiss VC2
Right after dismiss VC2, VC1 presents VC3
In the last step my transition goes bad as after dismissVC2 and beforePresentVC3, VC1 is visible during transition
How can I fix this problem or is it even possible??
NOTE: I want VC1 in window herirarchy so that I can go to VC1 from VC3
I think you're getting into some trouble with no sense. You could easily have a hidden navigationController and create and stack every VC and then move around with
self.navigationController popToViewController: animated:
or
self.navigationController pushToViewController: animated:
then you could move from 1 to 3, or 3 to 1 with no problem. If you created all the VCs and are available to access from any of the 3 vcs
Hello I am new to iOS and have a question about navigating through my views.
I am using IB wiring up the PREVIOUS and NEXT buttons in the nav bar that pushes my views. This all works fine. However I am having trouble finding out where exactly what I need to do or where I need to place the code so I can skip over a view. To simplify my situation...
-I have 1 Nav Controller and 4 View Controllers named VC1, VC2, VC3, VC4. Each VC has a .H/.M
-Starting from VC1, they follow one after the other.
Say I want to skip VC3 and jump right to VC4 based on a setting in VC2. Where would I put the code to do this? Would I need to unhook the IBAction method from the NAV buttons at VC3?
I do apologize if this has been covered before. If there is a tut or if you know of a post that answers this, please let me know. I did do a search but the search was returning generic posts probably due to me using the wrong terminology.
Thanks in advance.
A couple of thoughts:
If you want to push from VC2 to either VC3 or to VC4, rather than having VC3 immediately push to VC4 in special cases, I think it's better to just have VC2 push directly to the appropriate view controller. Thus you might have an IBAction in VC2 that would do this for you:
- (IBAction)pushToNext:(id)sender
{
BOOL skipToVC4 = ... // put in whatever logic you'd use to bypass VC3 and go directly to VC4
UIViewController *nextController;
if (skipToVC4)
{
nextController = [self.storyboard instantiateViewControllerWithIdentifier:#"VC4"];
// obviously, if using NIBs, you'd do something like:
// nextController = [[ViewController4 alloc] initWithNibName:#"VC4" bundle:nil];
}
else
{
nextController = [self.storyboard instantiateViewControllerWithIdentifier:#"VC3"];
}
[self.navigationController pushViewController:nextController animated:YES];
}
This way, when you pop back from VC4, you'll pop back directly to the appropriate view controller (e.g. if you pushed from VC2 to VC4, when you pop, you'll pop right back to VC2 automatically.
And, obviously, if you're using storyboards, rather than manually invoking pushViewController, you could have two segues from VC2 (one to VC3 and one to VC4), give them appropriate identifiers, and then just invoke performSegueWithIdentifier to segue to the appropriate view controller. But the idea is the same: You can define an IBAction that performs the appropriate segue depending upon whatever logic you so choose.
You say that you have "PREVIOUS and NEXT buttons in the nav bar that pushes my views", I wonder about your "PREVIOUS" button. Is that doing a popViewControllerAnimated? Generally, a "NEXT" button will push to a new view controller, but the "PREVIOUS" button should not push to the previous view, but pop back to it. If you don't pop back, you can end up with multiple instances of some of your prior view controllers. Thus, the "PREVIOUS" button should be linked to an IBOutlet that does something like:
- (IBAction)popToPrevious:(id)sender
{
[self.navigationController popViewControllerAnimated:YES];
}
When popping back, you'll obviously pop back to the view controller that you pushed from. If you want to skip a few of the view controllers as you're popping back in iOS versions prior to 6.0, you would use popToViewController or popToRootViewControllerAnimated. For example, let's say that you pushed from VC1 to VC2, to VC3, to VC4. If you want to pop back from VC4 all the way to VC1, you would hook up and IBAction in VC4 like:
- (IBAction)popToRoot:(id)sender
{
[self.navigationController popToRootViewControllerAnimated:YES];
}
Or, if you wanted to pop back from VC4 to VC2, you would
- (IBAction)popToVC2:(id)sender
{
for (UIViewController *controller in self.navigationController.viewControllers)
{
if ([controller isKindOfClass:[ViewController2 class]])
{
[self.navigationController popToViewController:controller animated:YES];
return;
}
}
}
You can avoid this iteration through the navigationController.viewControllers if you passed a reference of VC2 to VC3 and then again to VC4, but sometimes the above technique is easier.
By the way, if you're supporting iOS 6 and above, only, and are using storyboards, you can also use unwind segues, which are a more elegant way of popping back to a particular view controller. But it's not clear whether (a) you're using storyboards; and (b) you're supporting iOS 6 and above only, so I'll refrain from a discussion of unwind segues at this point.
First:
Show us some code, where you are pushing new view controllers, maybe your whole navigation controller code
Second (Solution):
I assume:
Your prev/next buttons are linked to your navigationController class
you have the appropriate methods (prevPressed:/nextPressed:), which are called, when you click one of the buttons
I can help you with the following:
you know which controller is visible at the moment with the visibleViewController #property
each time you click on a button in the navBar you can ask the visibleViewController which next/previous view controller should be pushed/popped
Best solution would be, if all of your controllers VC1/2/3/4 are a subclass of a viewController class, which defines a method in it's interface:
- (Class)nextViewControllerClass;
- (Class)previousViewControllerClass;
and in the implementation:
- (Class)nextViewControllerClass {
return [VC4 class];
}
- (Class)previousViewControllerClass {
return [VC1 class];
}
And in your navigationController code the do this:
- (IBAction)next:(id)sender {
UIViewController *nextViewController = [[[self.visibleViewController nextViewControllerClass] alloc] init];
[self pushViewController:nextViewController animated:YES];
}