I have a 3 viewcontroller navigation where A presents modal controller B, which presents modal controller C all via segues. C has an unwind segue back to B. It also has an unwind back to A. When I perform action for C to unwind to B, it unwinds but then pops B and goes back to A. This is not what I want, I want it in this case to stay on B. Below are the segues VC C uses.
unwindCancel is for when user clicks on a collectionViewCell and goes back to VC B.
prepareForUnwind is just a standard "cancel" button to VC A.
Below is code for didSelectItem to call the unwind in VC C. Below that is prepareForSegue in VC C.
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
[self performSegueWithIdentifier:#"unwindCancel" sender:self];
}
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if ([segue.identifier isEqualToString:#"unwindCancel"]) {
GalleryDetailViewController *detailVC = segue.destinationViewController;
detailVC.colletionCount = self.indexPathToPass;
}
}
VC B unwind in .m file
-(IBAction)unwindCancel:(UIStoryboardSegue *)segue{
[self.collectionView scrollToItemAtIndexPath:self.colletionCount atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
}
VC A unwind in .m file
-(IBAction)prepareForUnwind:(UIStoryboardSegue *)segue {
}
When going from C to B, don't use an unwind segue just have C call dismissViewController. If you're committed to using unwind segues, look here specifically section entitle How an Unwind Segue Determines its Destination View Controller
I guess you confused an unwind-segue's identifier with unwind-segue's Action method.
If you build an unwind-segue with "prepareForUnwind" action, and then you change this unwind-segue's identifier to "unwindCancel".The problem would appear.
Just make sure the unwind-segue's identifier matches it's action method.
Related
I have 3 MVCs and name them A, B, C here.
A is the main MVC with a button "Menu" connected to B with popover segue.
A also connected to C with a manual show segue.
B is a popover MVC with a button "Detail" connected to A with unwind segue.
C is the detail MVC with detail info.
Inside the unwind function of A. I call performSegueWithIdentifier to show C.
Expected behavior is
Click "Detail" button in B
B disappear and A show up
C show up
But running the app I got.
Click "Detail" button in B
B disappear and A show up
C show up
C disappear and A show up
C show up and disappear suddenly which is not what I want.
Some additional info
Popover B is needed for more buttons.
A is embeded in a UINavigationController. Connecting A -> C rather than B -> C, for a Back button on top of C.
Seems unwind function is not the correct place to call performSegueWithIdentifier.
UIKit will pop view controller after calling the unwind function.
Thus push new view controller inside unwind function will pop quickly.
The solution is to delay performSegueWithIdentifier.
Solution 1: NOT WORKING FINE
Adding an bool instance and inside viewDidAppear use this instance to determine if we perform segue.
Won't work if B controller is a popover. After B popover disappear, viewDidAppear is not called for A controller.
Solution 2: WORKING
Push performSegueWithIdentifier into main queue.
#IBAction func unwind(segue : UIStoryboardSegue) {
dispatch_async(dispatch_get_main_queue()) {
self.performSegueWithIdentifier("SomeSegue", sender: self)
}
}
you can easily switch between the viewControllers by assigning storyboard id to them using below code ..
// you need to create UIStoryboard object by giving name of your storyboard
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
// here you need to create storyboard ID of perticular view where you need to navigate your app
UIViewController *vc = [mainStoryboard instantiateViewControllerWithIdentifier:#"viewContIdentifire"];
// if use presentViewController this will not enables you to go back to previous view
[self presentViewController:vc animated:NO completion:nil];
**// OR**
// using pushViewController lets you to go back to the previous view
[self.navigationController pushViewController:vc animated:YES];
Or still you want to work with segue so must gain control over them by implementing its delegate method below so they perform accordingly.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"segueName"]) {
// perform segue
[self performSegueWithIdentifier:#"SegueIdentifier" sender:self];
}
}
happy coding .. :)
I've just figured out what is an unwind segue and how to use it with the great answers from this question. Thanks a lot.
However, here's a question like this:
Let's say there is a button in scene B which unwind segues to scene A, and before it segues I want something to be done, such as saving the data to database. I created an action for this button in B.swift, but it seems it goes directly to scene A without taking the action appointed.
Anyone knows why or how to do this?
Thank you.
You can do it the way you describe, or by using a prepareForSegue override function in the viewController you are unwinding from:
#IBAction func actionForUnwindButton(sender: AnyObject) {
println("actionForUnwindButton");
}
or...
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
println("prepareForSegue");
}
The first example is as you describe. The button is wired up to the unwind segue and to the button action in Interface Builder. The button action will be triggered before the segue action. Perhaps you didn't connect the action to the button in interface builder?
The second example gives you have access to the segue's sourceViewController and destinationViewController in case that is also useful (you also get these in the unwind segue's function in the destination view controller).
If you want to delay the unwind segue until the button's local action is complete, you can invoke the segue directly from the button action (instead of hooking it up in the storyboard) using self.performSegueWithIdentifier (or follow wrUS61's suggestion)
EDIT
you seem to have some doubts whether you can work this by wiring up your button both to an unwind segue and to a button action. I have set up a little test project like this:
class BlueViewController: UIViewController {
#IBAction func actionForUnwindButton(sender: AnyObject) {
println("actionForUnwindButton");
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
println("prepareForSegue");
}
}
class RedViewController: UIViewController {
#IBAction func unwindToRed(sender: UIStoryboardSegue) {
println("unwindToRed");
}
}
BlueViewController has a button that is connected in the storyboard to BOTH the unwindToRed unwind segue AND the actionForUnwindButton button. It also overrides prepareForSegue so we can log the order of play.
Output:
actionForUnwindButton
prepareForSegue
unwindToRed
Storyboard:
EDIT 2
your demo project shows this not working. The difference is that you are using a barButtonItem to trigger the action, whereas I am using a regular button. A barButtonItem fails, whereas a regular button succeeds. I suspect that this is due to differences in the order of message passing (what follows is conjecture, but fits with the observed behaviour):
(A) UIButton in View Controller
ViewController's button receives touchupInside
- (1) sends action to it's method
- (2) sends segue unwind action to storyboard segue
all messages received, and methods executed in this order:
actionForUnwindButton
prepareForSegue
unwindToRed
(B) UIBarButtonItem in Navigation Controller Toolbar
Tool bar buttonItem receives touchupInside
- (1) sends segue unwind action to storyboard segue
- (2) (possibly, then) sends action to viewController's method
Order of execution is
prepareForSegue
unwindToRed
actionForUnwindButton
prepareForSegue and unwind messages received. However actionForUnwindButton message is sent to nil as viewController is destroyed during the segue. So it doesn't get executed, and the log prints
prepareForSegue
unwindToRed
In the case of (B), the viewController is destroyed before the method reaches it, so does not get triggered
So it seems your options are...
(a) use a UIButton with action and unwind segue
(b) trigger your actions using prepareForSegue, which will be triggered while the viewController is still alive, and before the segue takes place.
(c) don't use an unwind segue, just use a button action. In the action method you can 'unwind' by calling popToViewController on your navigation controller.
By the way, if you implement a toolBar on the viewController (not using the navigation controller's toolbar) the result is the same: segue gets triggered first, so button action fails.
If you are able to perform unWind Segue Successfully. Then the method in destination View Controller is called just before the segue take place, you can do what ever you want in source viewcontroller by using the segue object.
- (IBAction)unwindToThisViewController:(UIStoryboardSegue *)unwindSegue
{
CustomViewController *vc = (CustomViewController*) unwindSegue.sourceViewController;
[vc performAnyMethod];
[vc saveData];
NSString *temp = vc.anyProperty;
}
if you want your logic in source Controller then implement prepareForSegue in Scene B and set the unWind segue Identifier from Storyboard > Left View hierarchy Panel > under Exit in Scene B.
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if([[segue identifier] isEqualToString:#"backToSource"])
{
NSLog(#"Going Back");
}
}
At first, you should call the send data function in prepareForSegue method.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if([[segue identifier] isEqualToString:#"UnwindIdentifier"]) {
// send data
}
}
If you don't want to let unwind segue happen before getting response from the server, you should override
- (BOOL)shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender
method and return NO;. Then you can perform segue manually when you get the server response by calling:
[self performSegueWithIdentifier:#"UnwindIdentifier" sender:sender];
I am connecting three different views to one view and I am trying to create a back button that goes back to the view that I came from.
Example:
View A, B and C are connected to view D. I want to create a back button that goes back to say B, if I went to D from B. If I went to D from C, I want that button to go back to C and so on. How do I do this programmatically?
Here's some code:
On the sender we are using
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"SegueA"]) {
ViewController *destViewController = segue.destinationViewController;
destViewController.segueName = #"SegueA";
}
}
On the receiver side, we are using the following code :
- (IBAction)backBtn:(id)sender {
if([_segueName isEqualToString: #"SegueA"]){
[self performSegueWithIdentifier: #"SegueAA" sender:self];
}
So we are using a segue to go from A to D and then, if SegueA is identified we want to return via a segue from D to A called SegueAA.
Assuming you have UIViewController instead of UIView, you can use
[self.navigationController popViewControllerAnimated:YES]
You need to make a manual segue. You do this by making a segue from one view to another and then giving it a name in the interface builder.
Control Drag from one view to another
Under the "manual" segue type you probably want to use push
Click on the segue and go to properties and give it a name under the "Identifier" field
Then you can call it like so:
[self performSegueWithIdentifier:#"initalLegalSegue" sender:self];
(this block for example would launch my "initialLegalSegue" manually by code.)
With modal segues, I've been using this:
This goes back one view controller:
[self.presentingViewController dismissViewControllerAnimated:YES completion:nil];
This goes back two view controllers:
[self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil];
I have a view controller with 2 different segues that goes to 2 different view controller,and i have to implement the cancel button in both the controllers.When i press the cancel button,in both the controller,the view will return to the initial view controller.My question is how can i implement the buttons?When i try with this code the compiler warning:Multiple declaration of method "cancel:" found and ignored.Thank you.
interface:
-(IBAction)cancel:(UIStoryboardSegue *)segue;
-(IBAction)done:(UIStoryboardSegue *)segue;
-(IBAction)cancel:(UIStoryboardSegue *)segue;
implementation:
-(IBAction)done:(UIStoryboardSegue *)segue
{
if([[segue identifier] isEqualToString:#"ReturnInput"]){
AddSightingViewController *addController = [segue sourceViewController];
if (addController.birdSighting) {
[self.dataController
addBirdSightingWithSighting:addController.birdSighting];
[[self tableView]reloadData];
}
[self dismissViewControllerAnimated:YES completion:NULL];
}
}
-(IBAction)cancel:(UIStoryboardSegue *)segue
{
if([[segue identifier] isEqualToString:#"CancelInput"]){
[self dismissViewControllerAnimated:YES completion:NULL];
}
}
I'm not sure of what you're trying to do. But I think the cancel method needs to be in the 2 child View Controllers, not in the main one. One for each controller (and one cancel button for each view). That way you won't have any problems with multiple declarations of a method.
From your code I conclude that you are using (or want use) exit segues for canceling.
First, you should only have one method declaration and implementation for your cancel method in the initial view controller. In your storyboard create exit segues by control-dragging from your cancel buttons to the green exit icon blow the view controller and select the cancel method defined in the initial view controller. Do that for both view controllers. You should also give your exit segues different identifiers in your storyboard (you need to select the segue in the Document Outline to change its identifier).
Then your cancel method in your initial view controller can look something like this:
-(IBAction)cancel:(UIStoryboardSegue *)segue
{
if([[segue identifier] isEqualToString:#"CancelInput1"]) {
// Do something
} else if([[segue identifier] isEqualToString:#"CancelInput2"]) {
// Do something different
}
}
If you don't want to do anything when canceling just leave the method empty.
If you wan't to go back you need to implement an unwind segue.
To do this, define a method to go back on the original view controller (the one you want to go back). You can leave the method empty.
- (IBAction)methodName:(UIStoryboardSegue *)segue
{
}
Then on IB ctrl + drag from the button (or from the view controller) to the green "exit" icon. Select the methodName from the popup menu. If you did it from the view controller set the identifier on the segue and call it with performSegueWithIdentifier: from the button action.
Considerations:
The method name will be detected in every view controller on the storyboard.
You can define the same method name in different view controllers, but when you execute the unwind segue, you will go back to the most recent on the navigation path.
I have a problem,
The following is my StoryBoard,
the first Controller is a TabBarController,
and it relation with A (ViewController).
A is a ViewController,
B is a NavigationController, A change page to B by modal segue
C is a ViewController, C will change to another page by push so I need a NavigationController
OK, I want to pass value from A to C,
now I can pass value from A to B by prepareForSegue,
However, because B and C have relationship but not segue,
So I can't pass value from B to C by prepareForSegue!!!
How can I pass value between NavigationController and ViewController with StoryBoard?
The Storyboard image is a little misleading here.
When you segue to B, actually you are segueing to the B/C combo as NavControllers always have at least one viewController in their stack (which is their topViewController and their [viewControllers objectAtIndex:0]).
So you do have a relationship directly from A to C.
How you access that controller depends on whether your segue is modal or push. In your case it is modal, but I will describe both so you can see the difference.
In either case, to pass data to C, you need to declare a property in it's header file
#interface CviewController: UIViewContrller
#property (assign) int dataFromA;
#end
push segue
In a push segue, it is actually C that is the destinationViewController, not B. In fact the push segue is governed by B, which is the UINavigationController for both A and C. The code behind the push segue is of the form
[self.navigationController pushViewController:otherViewController];
In AviewController's prepareForSegue:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
CviewController* controller = segue.destinationViewController;
[controller setDataFromA:self.data];
}
It is possible in the storyboard to make a push segue line between two viewControllers that do not share a common UINavigationController. However when you run this you will get a crash error:
'Could not find a navigation controller for segue 'pushC'. Push segues can only be used when the source controller is managed by an instance of UINavigationController.'
Behind every good push segue lies a Navigation Controller.
modal segue
The code hiding behind a modal Segue is the UIViewController method
- (void)presentViewController:(UIViewController *)viewControllerToPresent
In a modal segue to a NavController/ViewController combo, the destination viewController is whatever the segue line points to. If it points to a viewController, that is the segue.destinationController (and the UINavigationController will be ignored, which is not what you want here); if it points to a UINavigationController, as in this case, that will be it's destinationController. But it is still straightforward to access the viewController, as it will be the navigation Controller's topViewController.
In AviewController's prepareForSegue:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
CviewController* controller =
(CviewController*)[[segue destinationViewController] topViewController];
[controller setDataFromA:self.data];
}
Note that in this case we have to use old-style [[message passing] syntax]. If we use modern.property.syntax we get a compile error. That's because the program does not know the type of desinationViewController, and refuses to accept topViewController as a property of an unknown type. But it is happy to [send [real messages]] to an unknown type. We also have to (typecast*) to avoid compiler warnings.