I've got a UIViewController with two button, prev and next. When I push these button I re-instantiate the same viewcontroller passing it some variables and then I push it on the UINavigationController with no animation.
With this method my memory is always full cause, as far as i know, it is released only when I pop my viewcontrollers.
So my question is.. how could I implement this behavior? I need to free the memory when I load next (or prev) view controller
Build a custom Navigation controller and animate the transitions yourself.
Related
I am getting a data packet from push notification in my app delegate. If I get this push, I want to segue to appropriate view controller which is a a few VCs deep in my nav stack. It looks really choppy watching the app quickly segue 4 or 5 times to get to appropriate VC.
It looks like I want to create a new UIWindow to cover up my main window while this choppy transition happens. How can I do this with a new UIWindow (have it appear when we know a push is coming through and remove when we reach correct view controller)? Is there another better way to do this?
Thanks a lot!!
If you want to use another UIWindow to initiate this nav stack transition, all you'd have to do is in your application's keyWindow, show some kind of "progress" indication while the transitions are happening in a background window, and then all you'd have to do is set the keyWindow property on your AppDelegate. You can also transition this "setting" with whatever animation you'd like!
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.
From an initial ViewController I've modally presented a second ViewController using a ShowDetail segue in the storyboard and a performSegueWithIdentifier: method call. The problem is when I dismiss this modal ViewController with the method dismissViewControllerAnimated: the initial ViewController is reinstantiated calling the viewDidLoad again.
I've tried using a Push segue instead of the Show Detail and the initial ViewController keeps allocated in the background as it should.
What might be going on? The initial ViewController never even calls the memory warning method.
Have you tried unwindSegues?
***** Long explanation ahead, skip to solution if you want the quick way *****
First of all, if it is a ShowDetail, it is not a modal view. Do try to see which is your case.
Modal segues can carry information backwards, but are a bit more complicated than push ones.
If you are modally presenting it, you should use Present Modally instead of a ShowDetail.
A modal presentation will always take the top view position in the stack, and Show Detail does as well, depending in how your views are set. For instance, if you have a detail view in stack, IT will be replaced rather than the stack top view.
Try choosing up to a specific segue, I particularly recommend modal assuming you need more than simple pushes (Or the Show would have closed the problem, being the equivalent to the previous deprecated push. If you only need something simple, Show is the way)
Now we've cleared this, what probably is happening is that the view is being removes since Show Detail replaces views instead of pushing them, and it has to perform init again.
***** Solution: *****
The solution then should be not to lose the view when replacing, and reinitializing it, what dismissViewControllerAnimated: does. If you use unwind segues, though, the view should be replaced BUT retained by ARC.
The following link has the best explanation all over the net about how to use it:
What are Unwind segues for and how do you use them?
Is it bad practice to skip view controllers in a navigation stack?
In my example I have a UINavigationController (which is being presented modally) with three UIViewControllers (firstViewController, secondViewController and thirdViewController), most of the time the user will be accessing firstViewController, maybe tapping a row which will then load secondViewController and so on, but what if in some circumstances I want to load the second or third view controllers immediately but still keep the first view controller in the stack, so that the user can still go back to the firstViewController.
I can do this but it doesn't feel right - is this something I should avoid doing?
Yes, it's called deep-linking, and it's perfectly fine. It's quite commonly done for things like coming from an external URL or push notification.
I am new to iOS and wondering how to properly implement view controller unloading/reloading.
Right now my app has a NavigationController with a MainMenuViewController (custom view controller) set up as root view controller. During the course of app lifetime, new ViewControllers are pushed/popped on the Navigation Controller. This works fine, the appropriate ViewControllers are initiated (from NIBs) the first time they are pushed to the stack.
However, I now want to unload one particular ViewController when it is popped, then reload it automatically when it is pushed again.
I have added a [self release] to that ViewControllers viewDidDisappear: and it unloads, but when i try to push the view again, i get a message sent to dealloc'ed instance error and crash. Therefore, my questions are:
Is that a proper way to unload a popped ViewController?
How to check if a given ViewController is loaded or not?
How to force a reload? With loadWithNib:, then push onto navigation stack?
Regards,
Peter
Welcome to iOS programming. Your crash is a memory management issue. It may take you a bit to get the hang of it but memory management gets way easier if you just follow one rule:
an object needs to release anything it retains (alloc is equivalent to retain)
In this case, your view controller is releasing itself and it definitely did not retain itself. Here's how the sequence works with a navigation controller:
The navigation controller is initialized with a root view controller (the first one on its stack). Lets call this firstViewController
A user action tells firstViewController to initialize secondViewController and push it onto the navigation controller. In most cases, firstViewController will release the instance of secondViewController after pushing it. At this point, firstVC is done with secondVC. The navigation controller is now retaining secondVC
User touches the back button on the navigation bar of secondVC. The navigation controller will pop secondVC from the stack and release it. As long as no other object is retaining it, secondVC will get be dealloc'ed.
Now user is back in firstVC. They can do the same user action which will init and push a new instance of secondVC.
Hope that helps a bit.
I'd also recommend you (re)read the Apple docs and look at the sample code referenced in the framework docs.
http://developer.apple.com/library/ios/#featuredarticles/ViewControllerPGforiPhoneOS/Introduction/Introduction.html