In my iOS 5 project, using ARC and Storyboards, I feel that I have run into a strange behavior. I would like to confirm if what I am experiencing is in fact the default behavior AND if it can be modified.
I have a NavigationController with a RootViewController in story board. Neither of these is tied to a specific subclass. On RootViewController I have a button that is connected to a segue for a ListingViewController, which makes a static call to a web service (does not vary by user input). What I have noticed - at least in the simulator - is that when I press the button, go back, and press it again, the second time it loads unrealistically quickly! It seems as though the ListingViewController is being cached.
Is this supposed to be happening? What can I do to fix it?
Is this supposed to be happening? What can I do to fix it?
Why do you think it's broken? I haven't looked into whether the storyboard holds onto its view controllers, but it wouldn't be surprising if it does.
If you're doing something like making your web service request in -viewDidLoad, but you want it to happen every time the view appears, you should move that to -viewWillAppear or -viewDidAppear.
Related
My apps "short" description:
Basically an interactive storybook, I have a class that sets up a audio session and audio player which every other class(ViewControllers) in my app imports and calls a function or two to set the right sound to be played each time something happens(for instance.. user reads the story). Each ViewController has it's own .m and .h classes and uses them for animations and action handling. My app is only about 60 mb's in size (audio/images/code).
Now these ViewControllers are set up in a storyboard (they are 13 now) and are modal segued from one to the next one and then programmatically dismissed to go back.
When I run my app on my iPad now, I'm starting to get memory warnings and yes Instruments is showing me that my app is adding roughly about 40 Mb's for every ViewController that I segue to.
My questions are:
Do they reside in real memory no matter what I do? (I thought I wasn't holding any strong pointers to these view controllers).
Is there an easy way for me to dismiss one controller and still use a modal segue to get to the next one?(ran into troubles trying this)
Modal Segues are probably not the way I should be doing things in my App are they?!. They looked so nice and easy for my "storybook", but now they are giving me a very rough time.
Any other tips you can give me from what I described are appreciated.
Thank you.
Yes, as long as you present it modally. The presenter view controller keeps a strong pointer to the presented view controller. What you could do here is in the viewWillDisappear: release all the images and other views that might use memory !
You could instantiate your view controller using the method instantiateViewControllerWithIdentifier: and then presentViewController:animated:completion: like you would do with any view controller
It's up to you to decide. But you could easily mimic the animation if you wanted to.
If I understood everything correctly I would go with a singleton class kinda like 'AudioEngine' which is accessible from anywhere in any class. Then I would design all my viewcontrollers in my storyboard like you did. When I need to present modally another view controller, I'll do it using the answer of your 2nd question. If I still had a memory issue, I would try to cheat and keeps always 3 view controllers (like we do with the UIScrollView's infinite scroll) that I would reuse and I'll mimic the modal presentation using UIView's animation blocks.
I have a UIViewController that contains a UITabBarController with three tabs (each tab being a UINavigationController).
The problem that I am having is that in the simulator and the device, going from one tab to another takes a few seconds. I do not (yet) have a way to measure how long it takes, however, it is noticeable.
I wanted to understand how I can make my UITabBarController more responsive. Is the solution to implement my own UITabBarController??
UITabBarController is supposed to always be the outermost view controller in any hierarchy. If it isn't, you are always going to run into some kind of problems.
That said, the specific problem you describe may not be the result of your hierarchy. I would suggest investigating the code that is executed to display a new tab -- either with instruments if you do that, or with NSLogs if not.
I'm doing an iPad tech demo and I'm running into a serious technical problem.
I have an app concept that leverages UISplitViewController, but NOT as the primary controller for the entire app.
The app flow could be described roughly as this:
Home screen (UIViewController)
List->Detail "Catalog" (UISplitViewController)
Super Detail Screen (UIViewController but could conceivable also be a child of SplitView).
The problem is in the flow between Home and Catalog. Once a UISplitViewController view is added to the UIWindow, it starts to throw hissy fits.
The problem can be summarized at this:
When a UISplitView generates a popover view, it appears to then be latched to its parent view. Upon removing the UISplitView from the UIWindow subviews, you will get a CoreGraphics exception and the view will fail to be removed.
When adding other views (presumably in this case, the home screen to which you are returning), they do not autorotate, instead, the UISplitView, which has failed to be removed due to a CG exception, continues to respond to the rotation instead, causing horrible rendering bugs that can't be just "dealt with". At this point, adding any views, even re-adding the SplitView, causes a cascade of render bugs.
I then tried simply to leave the SplitView ever present as the "bottom" view, and keeping adding and removing the Home Screen from on top of it, but this fails as SplitView dominates the Orientation change calls, and Home Screen will not rotate, even if you call [homeScreen becomeFirstResponder]
You can't put SplitView into a hierarchy like UINavigationController, you will get an outright runtime error, so that option is off the table. Modals just look bad and are discourages anyway.
My presumption at this moment is that the only proper way to deal with this problem is so somehow "disarm" UISplitViewController so that it can be removed from its parent view without throwing an unhandled exception, but I have no idea how.
If you want to see an app that does exactly what I need to do, check out GILT Groupe in the iPad app store. They pulled it off, but they seem to have programmed an entire custom view transition set.
Help would be greatly appreciated.
Apple states:
The split view controller’s view
should always be installed as the root
view of your application window. You
should never present a split view
inside of a navigation or tab bar
interface.
This does mean it should be root view and not subview of another view. Even though they add:
You should never present a split view inside of a navigation or tab bar interface
That does not mean you can add it as a subview of any other controller either. (sorry)
I have a feeling that what you are experiencing is the byproduct of trying to do so. I am actually surprised that GILT Groupe's app did not get rejected. Apple has a tendency to enforce these HIG guidelines rather strictly lately. They (as you found out already) cause a rather nasty runtime error when you attempt to add them to a NavigationController.
I've solved this for myself... actually worked around... by presenting all other possible full screen views as modals of the SplitView...
This is an unsavory way of doing things in my book, but Apple leaves you little choice if you want to leverage a SplitView only "sometimes" within an app.
I had some success by creating a second UIWindow. I associate the UISplitViewController with that, and switch it out with the main window when I want to show the splitview. It seems to work they way I wanted, except for a slight delay in rotations and a log message about "wait_fences".
Unless your developing for jail-broken devices then bending apples rules/wishes isn't a good idea. Like Jann and Jasconius state above this means keeping a splitView controller view root, not over-using modals (vague) and not using multiple windows.
Also, the Gilt app is only available in the US
I'v been trying to find a solution too and have ended up programatically removing views from the window like Tuannd talks about but the landscape rendering bug is unforgivable.
#Jasconius, What is the max number of modals are you are presenting at any time?
I am struggling with this same issue. I've been trying various things poking at the UISplitViewController as a black box and see how it reacts.
I seem to have come up with a solution to my case which seems to be working satisfactorily.
The key appears to be that the first view added to the UIWindow is the only view properly initialized. All the problems I've had tend to stem from incorrect notification of the orientation of the device. The first view added, apparently has this correctly configured.
In my case I didn't want the UISplitView as the first view. The following is working for me.
The app delegate application:didFinishLaunching method is special. Adding the view to the UIWindow must occur here. If it is done elsewhere it does not get configured properly.
Essentially the magic sauce, is have the split view be the first view added to the window. Its then ok to remove it as long as you retain the UISplitViewController. From then on you can swap other views in and out, including the UISplitView and most things seem to be ok.
I've still run into a few issues. Popovers on views other than the split view are confused on the views frames and location of toolbar buttons and will display in the wrong location. I place then in a specific location and that seems to handle that case.
If a popover on the split view is still displayed, and you try to view another view, the orientation of the second view is confused and shows up sideways. If that view is accessed before the popup is displayed, all is well. I've fixed this my manually dismissing the popover before switching to any other view.
Here's the code if it helps. All the controllers are instance variables of appDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// This also seems to work as good magic. Seems to set orientation and size properties that persist.
[window addSubview:splitViewController.view];
[splitViewController.view removeFromSuperview];
[self switchToNewViewController:firstController];
[window makeKeyAndVisible];
return TRUE;
}
- (void)switchToNewViewController:(UIViewController *)newViewController {
[popoverController dismissPopoverAnimated:FALSE];
if (newViewController != currentViewController) {
[currentViewController removeFromSuperview];
currentViewController = newViewController;
[window addSubView:newViewController.view];
}
}
Just wanted to say that I was running into these same issues, found this forum topic, and followed the advice from g051051 above. This is working perfectly for me. I am not seeing any glitch, and no messages about wait_fences in the console of the device.
I simply used IB to create two UIWindow objects in the main XIB, created as normal the UISplitViewController and then also an instance of my other controller derived from UIViewController (which I am using for full screen display). I have simply hooked them up by attaching the rootViewController for each UIWindow to its appropriate controller.
In application:didLaunch...: method I can decide which window to send the makeKeyAndVisible method and which to set to hidden. When the user want to switch back and forth I simply have to send makeKeyAndVisible to one and set the hidden property on the other, that's all there is to it.
As indicated all of the rotation related messages are sent to each controller appropriately, regardless of which one is associated with the currently visible window.
Anyway, works great for me, and actually quite easy to set up.
I have a UIViewController that is pushed onto a UINavigationController and is currently displayed. When I go to start some asynchronous task inside the view controller, I can set hidesBackButton on self.navigationItem to YES, and the back button is hidden correctly.
As soon as the task is finished, and I set hidesBackButton back to NO (on the UI thread, I might add, I've made sure of this), nothing happens. The back button remains hidden.
Has anyone seen this before? What drives me especially crazy is that in my application (the same application), in a different UINavigationController hierarchy, the exact same code works correctly!
Are you calling hidesBackButton = NO from a thread? All UI operations should be done on the main thread, otherwise they won't have any effect.
i have not been able to replicate your problem on my machine. however, i faced a similar issue with tableviews even when i was updating my ui on the main thread. but calling setNeedsDisplay fixed that issue.
Can you try this and see if this works:
[self.navigationController.navigationBar setNeedsDisplay];
I guess this should work, you need to do the same, BUT ON THE NAVIGATIONBAR instead. please let me know if this worked - as i cannot test my solution because i never get this problem :-)
Have you tried forcing the view to refresh by calling setNeedsDisplay?
Maybe the OS is not picking up the changes instantly and you need to force it.
Have you tried using the setHidesBackButton:animated: method instead? Perhaps that has a slightly different behavior.
In my case I simply had to give a title to the view, as in:
self.navigationItem.title = #"Menu";
Marinus
I have had a similar issue recently. I tried literally everything I found in SO and other forums- nothing worked.
In my case there was a modally shown UINavigationController with a simple root controller which would push one of two view controllers (A and B) on top of the controller stack when the button A or B was pressed, respectively. Controller B was the one which was not supposed to show the back button. But still, sometimes it did, sometimes it didn't.
After hours of debugging, I managed to track it down. Controller A was a UITableViewController. Each time I selected a cell in this controller, the delegate would pop Controller A off the stack. BUT. I made use of a UISearchDisplayController as well. Turned out that popping the view while the search controller was still active messed up something in the navigation controller that made it impossible to hide the back button in Controller B afterwards (well, it eventually stayed hidden between viewDidLoad and viewDidAppear: but then it always turned visible).
So the solution (rather workaround) was adding this line to where Controller A was dismissed:
controllerA.searchDisplayController.active = NO;
// ...
// [self.navigationController popViewControllerAnimated:YES];
Hope this spares someone a couple of hours.
Greetings. I've got a nav-bar application that's misbehaving. I've got two buttons, one that shows all results from my database and another that shows a subset of my database. Of course, each button has its own action method. Both of these methods instantiate a view controller object of the same class.
If I start the app and only click the "all results" button, I do see all results. The goofy thing is that when I click the button for the subset of results (and see the subset of results), click Back on the nav bar, and then click the first button for the entire set, I see the subset again.
While debugging with break points all over the place, I noticed that the dealloc method of my results view controller doesn't get called. However, when I click Back and then click the all-results button, the alloc/init methods are indeed called again for my results view controller.
So even if I have a blatant memory leak, how is it possible that my freshly allocated/initialized view controller object has the same data as that of the previously instantiated view? Stepping through the code made this problem seem even more bizarre, as it appeared to be behaving properly...just yielding old data.
Any advice at all would be great. Thanks!
Calling "reloadTableData" on the table view should ensure the data is refreshed. Call that in the action methods.
Why do your buttons repeatedly instantiate the view controller? Why not have pointers to the view controllers as instance variables that you only have to set once and then can use at will?
This is just a wild guess, but it could be related to the reuse of tableViewCells. Try always creating a UITableViewCell, avoiding the reuse-identifier to see if the old data persists.
I figured out what was wrong a while ago and thought I would answer my own stupid question. :)
I had forgotten that I made my Database class a singleton and put a master pointer to "allResults" in the app delegate class.
Thanks anyway for your input. Every little bit helps me understand this new environment better.