I'm using storyboard and i want to know if there is a way to use a UINavigationController to navigate from A->B->A->B and so on. The UIViewControllers are the same but the info loaded in each one is different.
I tried using segues but the problem is that the info loaded into the classes is not saved. So when i do A->B->A and i go back to the root, the info of root is the info loaded in the 2ยบ A. Because i'm using storyboards i don't create instances of the UIViewControllers and i think that is the problem, i only use [segue destinationViewController] in prepareForSegue. I think that one solution would be stop using storyboards and use Xibs, because that way i would create an instance of each class every time they were loaded and that would solve my problem.
I just wanted to know if there is a way to do this using storyboard, because changing to Xibs, would need a lot of work. Any suggestions?
I've never tried to do A -> B -> A -> B before. But I have tried to do A -> A -> A, and that doesn't work. A limitation of Storyboards is that you can't segue to another instance of the same VC.
However what you can do is pretty easy - instead of writing up the button to triggering a segue in the storyboard, wire it up to a method and push the new view controller onto the navigation stack manually.
- (IBAction)buttonTapped:(id)sender {
UIViewController *viewControllerA = [self.storyboard instantiateViewControllerWithIdentifier:#"viewControllerAIdentifier"];
[self.navigationController pushViewController:viewControllerA];
}
Note that "prepareForSegue" won't get called here so you'll have to configure the new VC instance as needed.
Related
I have 4 ViewControllers in my storyboard. I want all of them to be able to access my "Settings" ViewController by performSegue.
Is it possible to have ONE segue to perform this, instead of ctrl + drag from each and every ViewController to my "Settings" ViewController?
No its not possible with a single segue. You need 4 different segues from 4 different ViewControllers. But you can do this programatically.
Make an extension for UIVIewController
extension UIViewController
{
func showSettingsScreen()
{
let storyBoard = UIStoryboard(name: "YourStoryBoardName", bundle:nil)
let settingsScreen = storyBoard.instantiateViewControllerWithIdentifier("YourSettingsViewControllerID")
self.navigationController?.pushViewController(settingsScreen, animated: true)
}
}
Now you can call showSettingsScreen() from any of your view controllers(Make sure this view controller has a navigation controller).
You cannot do that. A segue has only one source and one destination. You could programatically instantiate your Settings ViewController and display it either by using push or by using present. What you should think of though is why do you have to go to settings from so many places. It might be a sign of bad design and duplicate code. Usually applications have only one such button/action that can be accessed from multiple screens (by using some kind of container view implementation) or from only one screen.
I really dont think so there is a way to do so. U ought to connect ur SettingsViewController to all of your 4 View Controllers, add segue , and define a segue identifier which is used in
prepareForSegue:sender:
or
shouldPerformSegueWithIdentifier:sender:
methods. U can access segues through these identifiers. If u find "ctrl + drag from each and every ViewController to "Settings" ViewController " tasky you can opt for Navigation Controller as well. U just have to embed Navigation Controller in your storyboard and define Storyboard Id for every View Controller and you are done. Just use storyboard id of view controller to be instantiated and u good to go.
ViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:#"ViewController"];
[self.navigationController pushViewController:vc animated:YES];
Apart for assigning storyboard id you dont have to worry about storyboard ,No ctrl+drag thing.
I thought of one more elegant solution i.e. using Container View. You can take button to switch, SettingsViewController as common, in your Container View Controller while displaying every ViewController.
happy Coding..
There is one way to do this. Create a root view controller and matching view which contains a single embedded view. Add your segue to this root controller. Then in your app you switch in the other view controllers using standard child container techniques. This is pretty much the concept that UINavigationControllers use.
One advantage from this is that if you want to have common elements which are visible to all controllers then you can add them to your root controller.
But it all depends on what you are trying to achieve.
I am developing an application with iOS 9 based SDK , this is my first time I am working with Storyboards , I have 20 view controllers, each scene has Next / Previous buttons to go back and forward . I have a huge problem with going forward !. If I move from scene 1 to for example to scene 15 I received memory warning and then application crashes . I have searched and it seems there is method called unwind segue but it seems this is for going back ! it's something like dissMiss method .
I connect each scene with line in Interface Builder :
Here is segue's setting :
I would be grateful if you help me out .
EDITED :
I tried to present a view controller programmatically but result was the same ! .
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
WhatIsDino *vc = (WhatIsDino*)[mainStoryboard instantiateViewControllerWithIdentifier:#"WID"];
[self presentViewController:vc animated:YES completion:nil];
Seems like it's a problem of wrong approach, and not the storyboard.
Let me guess, since before storyboard you used to change your app's rootViewController to the next/previous screen once you tap on the arrow button. So previous screen are released and deallocated from memory once you set a new rootViewController.
And now you're presenting every next view controller modally, which involved creating new UIWindow and loads all the hierarchy of you screen and keeps previous underneath the new one so it holds the memory and you're getting out of memory crash.
Well, you can do rootViewController approach with a storyboard too since it's just another way to manage your screens while development. Storyboard offers additional features like segues, static table view cells, general tint color and so on. [UIStoryboard -instantiateViewControllerWithIdentifier:] is the method you might find interesting.
But I'd rather recommend you to check out the UIPageViewController, it's like a container for the screens. Unfortunately, it cannot have the segues to your scenes (because of the special way segues work) so you have to use -instantiateViewControllerWithIdentifier: method anyway. You can treat inner view controllers of UIPageViewController as you do with rootViewController before.
You can also navigate without segue and Its easy way I think.
If you want to navigate from Class1 to Class 2 then follow these steps.
1) In Class 1, Import Class2.
2) In your button Action, Write this code.
Class2 *next = [self.storyboard instantiateViewControllerWithIdentifier:#"Class2 Identifier name"];
[self.navigationController pushViewController:next animated:YES];
Do not forget to give Identifier name in story board that is "Storyboard ID" in Attribute inspector of particular class.
No need to add Segue,Your storyboard would look clean.
The problem is that you are adding view controller after view controller with modal presentation. That causes each view controller to be added on top of the previous one, and all of them accumulate, using more and more memory.
Using a navigation controller and a push also piles the view controllers on top of each other.
You will have this problem if you use storyboards, nibs, or create the view controllers manually.
If you have a design where the user can move through a large series of view controllers then you probably want to dismiss the previous one before pushing/presenting a new one.
You can probably dismiss the previous view controller without animation and then present the new view controller each time you want to display a new one and avoid the memory issue. i'd have to experiment with it to get the effect I was after, but that's what I would suggest.
I am trying to make a tabbed application in Xcode that allows the user to take a photo and edit it on the FirstViewController class and when they are done display it on the SecondViewController.
When I started the project, Xcode automatically made the two viewControllers for me in the storyboard. What I need now is to find the instance of the second viewController that was generated so I can call a method and pass an argument (the UIImage) from the first view controller to the second like this.
FirstViewContoller.m
-(void) passImageToSecondVC (UIImage *) img
{
[<instanceOf_SecondViewController> receiveImg: img];
}
SecondViewContoller.m
-(void) receiveImage (UIImage *) img
{
//Code to display the image received
}
What Im asking is how can I find the name of the instance of the SecondViewController (shown by <> in the example code) generated by Xcode so I can call this method.
Although I'm very close to just doing this programmatically which I find much easier I wanna learn how to do this through the storyboard also I'm very open to hear other solutions to this problem. Thank you!
There's no way to do this through the storyboard. You don't access the view controller by its name. Each view controller has access to the tab bar controller through self.tabBarController. You can access individual controllers from the tab bar controller's viewControllers array. So, to get a reference to the controller in the second tab, you would use self.tabBarController.viewControllers[1].
Use delegates pattern.
Make one vc be a delegate of the other vc and communicate data between them. I think It's a common scenario.
https://developer.apple.com/library/ios/documentation/General/Conceptual/DevPedia-CocoaCore/Delegation.html
I want to move to another viewcontroller in another storyboard and the view controller im in is not embedded in a navigationctroller.
Normally i would just instantiate the viewcontroller and push it to the navigationcontroller stack but since this is not possible i dont know what to do, and I cant seem to find any help on this.
Any suggestions?
It depends on what you're trying to achieve in the app, but a few options are: present it as a modal controller, create your own custom type of segue, replace the root controller in the app's window....
I'm moving my App to Storyboards and, so far, so good.
However, I've found something that I don't really understand and worries me. I would appreciate if someone can provide some insight on this.
My app uses a normal Navigation Controller. For moving "forward" to new View Controllers, I'm using custom segues; no problems there. However, there's a point in the App where I want to move back to the beginning of the Navigation Stack. I have also configured that "navigation" using a custom segue, for that, I created the segue in Interface Builder by dragging the last view controller to the first one (that already looks weird to me), and I've implemented the custom segue perform method in the following way:
-(void)perform
{
UIViewController *src = (UIViewController *)self.sourceViewController;
UIViewController *dest = (UIViewController *)self.destinationViewController;
[src.navigationController popToRootViewControllerAnimated:NO];
// Custom animation code here
}
... It works great. However, I don't understand why it works. In my mind, the custom segue should be instantiating a new instance of my first view controller and assign it as "dest", but it looks like the segue is smart enough to realize I want to navigate to a previous, existent, instance of a View Controller and, instead of creating a new instance, it assigns to "dest" the existing one.
Does anybody know if using segues in this way is ok? Is it possible that it works by chance but might stop working in the future? Am I wasting memory in anyway as the segue is instantiating a View Controller I'm not going to use?
Thanks a lot in advance!
Am I wasting memory in anyway as the segue is instantiating a View
Controller I'm not going to use?
Yes sir! By using a segue, you effectively allocate a new view controller as it's needed to set the DestinationController property for your custom segue. Test by yourself : add a static counter into your root controller, increment it each time this class is initialized and display it in your view : you'll see it getting incremented every time you pop to root using this trick.
Does anybody know if using segues in this way is ok?
As long as you're effectively wasting memory, no!
There's at least one solution to this problem : release the DestinationController of the segue in your (void)perform implentation. This is really quick to implement, but kinda ugly since you allocate and immediately release your view controller every time... even if it's better than just leaking it, it's not what I'd call a good practice!
To my mind, a better way to achieve what you want would be to not use a segue for that transition, just to use a button or whatever and call popToRootViewController:animated when getting a touch on this button.
Is it possible that it works by chance but might stop working in the
future?
For both the first solution I suggested and the way you're currently doing it, I see absolutely no reason : these are not complicated tweaks, just 'bad-implemented' standard navigation. The second solution is perfectly normal so no worries.