I have a fairly simple app thats a game for small children. There is a main screen and 5 separate levels. 3 of the 5 levels are made up of more than one VC where actions take place in the first VC in that row then code calls a modal segue to the next one in the line and so on till it reaches the end of the row and a modal segue is called linking back to the main screen. The levels that have only one VC just perform actions then segue back to the main VC.
Every segue in the app in modal.
Also every page (VC) has a home button that will segue to the main page if pressed
I set this all up in the StoryBoard and visually everything works as Id expect but when adding sound I realized that there seems to be a major problem.
If I now understand correctly (and maybe I dont) modal segues dont actually replace the current VC with the newly requested one but rather slide the newly requested one over top the original and make it the visible display.
Currently I go from main to level 1. Level 1 does some stuff and plays some sounds that repeat via a timer. If I segue back to main visually everything is fine except the sounds being played by the timers in level 1 VC continue to play and xCdoe give me the following error quite a few times
2013-01-21 22:16:07.901 TTBetaDev[678:c07] Warning: Attempt to present <MainMenuViewController: 0x7e02f40> on <BonusViewController: 0x7ecbfa0> whose view is not in the window hierarchy!
Below is a screenshot of my storyboard in case I havent explained the layout well enough.
How should this be set up to allow the navigation I would like? A what steps will I need to take to apply that to the what I already have built in the storyboards? Or will I have to re-do all my storyborad work?
I tried apples VC documentation but I couldnt understand what relates to what Im trying to do.
COuld someone please help explain this to me
You have segues going forwards AND backwards. You shouldn't do this.
e.g. Look and Main and VC 2.
You have a segue going from Main to VC 2. This means that Main will present VC 2 as a modal view controller.
When Main does this though it is still on the stack underneath VC2.
Then you have a segue from VC2 to Main. This means that VC2 will create a new Main and present it modally too. If you continue using the app you will have multiple instances of main and all the other VCs and memory consumption will rocket.
What you need to do is delete ALL the segues that go backwards. (i.e. like the one from VC2 to Main)
Then when you want to get back to main from VC2 you have to dismiss VC2.
i.e.
in Main...
//present VC2
[self performSegueWithIdentifier:#"VC2Segue" sender:nil];
//dismiss VC2
[self dismissViewController:vc2ViewControllerInstance];
or in VC2...
//dismiss VC2 from itself
[self dismissViewController:self];
The main thing though is that you can't use segues to go backwards.
TL:DR
Nothing should segue INTO Main. Any segues that go into the left hand side of main should be deleted and dealt with properly.
Related
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?
The Problem
I'm currently building an iPad game using SpriteKit. The gameplay is driven by sound provided by EZAudio. After running the Instrumentation tools to profile my app, I noticed that whenever the GameViewController is shown memory allocation jumps up. When I repeatedly show the screen (5+ times) it crashes the app. My project uses ARC.
Navigation
The navigation consists of 4 ViewControllers:
MenuViewController: This shows the menu
CharacterSelectionViewController: It lets you a pick a character to use
GameViewController: This lets you play a game with the player chosen
ScoreViewController: It shows you the score you achieved in the game
1 - MenuViewController
From here you can navigate to CharacterSelectionViewController via a Show (e.g. Push) segue.
2 - CharacterSelectionViewController
You can navigate to GameViewController via a Show (e.g. Push) segue. There is also a back button that goes back to MenuViewController with the following code:
[self.navigationController popViewControllerAnimated:YES];
3 - GameViewController
It first shows a 5 second countdown (using NSTimer)
The game starts with the character chosen in CharacterSelectionViewController
The game can be paused, allowing you to quit and go back to MenuViewController via a manual Show Detail (e.g. Replace) segue.
When the game ends, a manual Show (e.g. Push) segue is called that navigates to the ScoreViewController.
It's view hierarchy consists of three sets of view - one for the countdown, one for the pause menu and one for the game. These are subsequently shown/hidden. See the view hierarchy below:
4 - ScoreViewController
This allows you to quit or restart the game. When quit it pressed it performs a Show Detail (e.g. Replace) segue to MenuViewController. If restart is pressed it performs an unwind to CharacterSelectionViewController.
Responses
Please provide answers regarding:
How this kind of leak could occur
Any observations you have from the allocation and leaks screenshots
Allocation
Below, you can see the increasing allocations as I cycle through the apps screens to repeatedly show the GameViewController. I used Mark Generation to be able to show the increase in memory allocations.
Leaks
Here you can see the memory leak that occurred. This is ordered by size.
Ignore the leaks for the moment; fix the generational accretion first.
Is that generation snapshot representative of what is left after a typical snapshot? Typically, you'd want to show view controller, take snapshot, hide then show view controller, take snapshot, etc... as many times as you can without crashing (or 10 times if it doesn't crash).
Then look at generation 3 or 4 as that'll be the most stable representation of per-generation accretion.
If it is representative, it looks like you are leaking everything that the view controller would normally allocate. Ultimately, you are looking for the "root" of your object graph that is keeping everything around. Fix the reason why the root is sticking around and the rest'll likely go away.
I wrote a weblog post about this. It is a bit outdated, but the analysis workflow remains the same.
http://www.friday.com/bbum/2010/10/17/when-is-a-leak-not-a-leak-using-heapshot-analysis-to-find-undesirable-memory-growth/
How are you unwinding from your various view controllers? I note that you mention that when the game ends you're pushing another VC onto the stack, but I presume this VC chain will at some point unwind back to your initial menu? (In essence, I wonder if you're just looping around, hence adding new VCs to the stack everytime you play a game.)
To create an un-wind segue, simply create an empty method in the destination VC (i.e.: your main menu) as such:
- (IBAction)unwindToMainMenu:(UIStoryboardSegue*)sender
{
// Intentional NOP
}
(N.B.: Make sure it's also listed in the header.)
You can then call this as you would any other segue in your storyboard by dragging from the source object in question to the exit option at the top of the VC that contains the source object in the storyboard. This will present you with a list of segues to choose from. (You can verify that the segue is setup correctly by selecting the source object in the storyboard - the Connections inspector should list the unwind segue within the Triggered Segues section.)
I created a storyboard for my app which contains the following:
Initial view controller on my storyboard is a Tab Bar Controller (let's call it myTabCtrlr)
myTabCtrlr has forward segues pointing to several other controllers:
a. First segue points to a custom UIViewController (let's call it vc1) on which I create an interactive UIView (let's call it popview1) which is initially hidden. There's a button (let's call it showPopView1) on vc1's view which when clicked would show popview1
b. Second segue points to a navigation controller, which embeds a view controller with 3 buttons, each pointing to an (end) controller.
c. Third segue points to another navigation controller with a similar setup as (b)
On several of these (end) controllers, there's a button similar to vc1's showPopView1 that when tapped, I'd like to switch back to vc1 and programmatically bring up popview1, which I'm doing as follows (but it's not working):
myTabCtrlr.selectedIndex = 0;
//I get a handle to vc1 then
vc1.popview1.hidden = NO;
When I do that, it goes back to the first tab and shows vc1 view (which is good) but it does not show popview1. I tried many different ways to do it but no luck.
Note that if I'm actually on vc1 and I tap the showPopView1 button, then popview1 comes up normally.
Does anybody know why that is the case? This only started after I transitioned to using storyboard. thanks.
After spending hours looking at various ways to solve this problem, and focusing on reverse segues and similar methods, I was able to solve it using a totally different method.. I wanted to share this with others so nobody has to waste so much of their time (although I noticed slow response to my post. Maybe I didn't make the subject attractive enough :)..
It's a really simple solution, but quite effective. I used a Singleton pattern object. When coming from the rest of the tabs, I set a flag in the singleton that vc1 checks in its viewWillAppear method, shows popview1, and immediately resets the flag.. works like a charm!
Using:
Xcode 4.6
Storyboards
ARC
Model segue to SecondViewController
I have an app that has the main ViewController that loads a new veiwController when the device is rotated to the right. When the app starts everything works great. If I rotate the device, then back which unloads the secondview controller, about 15-20 times the app is very slugish. I have narrowed down that it only happenes when the seconed view controller is loaded and only when i rotate the device a nunmber of times. I also have narrowed down that is is a memory issue. I installed an app that keeps track of the memory used and available. My memory goes from 400mb to 900mb used when i rotate the device a number of times. I am trying to give as much info as I can. Each view has 8 NSTimers that fire every second.
Is there a way to programmatic unload a view, to make sure is is being unloaded?
I have included this code to ensure the loading and unloading:
`- (void)setView:(UIView *)aView
{
NSLog(#">>> Entering %s <<<", PRETTY_FUNCTION);
if (!aView) // view is being set to nil
{
NSLog(#"Should be unloading now");
}
[super setView:aView];
NSLog(#"<<< Leaving %s >>>", __PRETTY_FUNCTION__);
}
log result:
2013-04-22 16:42:03.588 xxxxxxxx[xxxxxxx] >>> Entering -[GraphViewController setView:] <<<
2013-04-22 16:42:03.589 xxxxxxxx[xxxxxxx] <<< Leaving -[GraphViewController setView:] >>>
`
I am not sure what I need to be looking at to correct this.
Any "points" in the right direction will be very appreciated .
Thanks
You haven't given much information about how you "unload" SecondViewController. Are you doing a modal segue to it as well? If so, that's your problem -- every time you do a segue, you instantiate a new view controller, and if these are modal segues, the presented controller has a strong pointer to the presenting controller, so none of these controllers will ever get deallocated as you go back and forth.
As a rule, you should never go backwards in a storyboard using anything but an unwind segue. So, the solution to your problem is to use an unwind segue to go from SecondViewController back to MainViewController -- this will actually go back to the same instance of MainViewController that you came from, and SecondViewController will be deallocated. If you don't know how to make an unwind segue, I will edit my answer to show you how.
After Edit:
To make an unwind segues, you do two things. In the controller that you're going back to, you add a method -- the two important things are that it be an IBAction, and that it has a single argument that's typed to UIStoryboardSegue*. It doesn't matter what you call it, and it doesn't even need to have any code inside it, though I usually put in a log statement just to be sure it's called. Then, in IB in the controller you're unwinding from, you control drag from your UI element like a button or table view cell (or from the controller itself if you want to fire it from code), down to the green Exit icon at the bottom of the scene -- it's important to note that you are dragging from a UI element to the exit icon in the same controller, not between controllers. When you let go of the drag over the exit icon, you will see any methods you created with the signature I mentioned above. Choose the one you want, and that's it. You can implement prepareForSegue in the source controller just like any other segue if you want to pass any information back to the destination controller.
I am just looking for a sanity check here.
I have a screen that the user passes through on the way into the main application. That screen can be navigated back to from almost anywhere in the system.
As it stands I am just presenting ViewControllers without using a NavController to manage them (it does not seem applicable for most of my app, since screens are not necessarily sequential or related to one another).
My question is, if I have presented VC1, then navigate to other screens, and finally want to present VC1 again, I am doing something like:
[self presentViewController:[self.storyboard instantiateViewControllerWithIdentifier:#"VC1"] animated:YES completion:nil];
Is this bad form? Am I leaking memory by creating a bunch of VC1 instances or is there some magic that uses the previously created one?
If it is bad form, how do I get back to the original VC1 to reuse it?
Thanks for any input.
I think you pegged it: It's not a great idea to have multiple instances of the same view controller in memory at the same time. Every time you instantiate a new view controller and present it modally, you'll consume more memory.
The most elegant solution is the iOS 6 unwind segue. But most of us would be unwilling to give up on iOS 5 support quite yet.
If you need to support iOS 5, you could contemplate using navigation controller, but hide the navigation bar if you don't like it in your user interface. Then replace modal segues with push segues and now you can do popToRootViewController whenever you want to return to the main view controller.