I am getting this error from swift and I am unsure why there is only 1 view controller that actually has this occurring the error is whose view in not on the hierarchy. My question is why would this occur for one of the view controllers presented from this primary viewcontroller button but not the other view controller linked from this primaryview controller? Is there something that could cause this to occur specifically. I am trying to present this modally and it is being called programmatically so that I can pass data objects.
For me it just seems very strange that this would occur for one viewcontroller presented from this viewcontroller but not the other. The only thing I did which I didn't think would effect this was duplicating the primary viewcontroller but again why would one work but not the other? The problem is specifically happening with iOS.
Should have checked the buttons to make sure they were linked correctly. I realized after reading a few of the same questions that I should check the button selectors under the view controller references tab to see what was linked to what. I had 2 actions doing 2 different things for 1 button by accident I must have miss clicked the control drag function.
Related
I would like to update my UILabel on click the button of ContainerView contains table ViewController. When I try to do this UILabel's outlets reference shows nil value exception. I am using Swift3 with Xcode8
Most probably the problem you are seeing is due to the fact that the view that owns this label on another view controller is still not loaded.
This happens often, basically because views owned by a view controller are instantiated in a lazy manner, this means that they are loaded only when required.
To fix that before setting the value on the label, just preload the view by doing something like.
_ = another_viewcontroller_instance.view
In this way you are forcing the destination view controller to load the view and creating all the necessary connection on the xib.
Even if this fix works, this is not a good way to deal with this kind of pattern (sending info from a VC to another), but since you didn't gave us any further detail this is the only solution I have.
So I am trying to programmatically change views when some condition is triggered.
I have created a simplistic project, whereby I want to change to View 2 from View 1, once View 1 has loaded. In reality, there is some logical operation that checks if some variable is true, then it invokes the performSegueWithIdentifier function, however to keep this as simple as possible I have removed that code.
The steps I have performed are, firstly to create two views:
I then click View 1, and inspect its properties and then created a manually triggered segue to View 2
I selected the 'Show' option, so now my Views are connected by a segue
Then under attribute inspector, I give the storyboard segue and identifier of "GoToView2".
From there I go to the ViewController.swift file, and in the viewDidLoad function. I insert performSegueWithIdentifier code:
self.performSegueWithIdentifier("GoToView2", sender: self)
However, when I then run the code. View 2 does not load, and only View 1 appears in the simulator.
Any help and explanation would be greatly appreciated.
I have had the same problem with attempting to perform a segue inside the viewDidLoad function, and the error that comes up seems to be that the view you are attempting to load with the segue is not in the window hierarchy.
Changing the call to viewDidAppear seemed to fix the issue as mentioned in this other post: whose view is not in the window hierarchy (note the language is objective-c not swift, but it can be translated).
It seems you have to be careful at what point in the view lifecycle you want to change it to another view controller - at viewDidLoad all the views in the storyboard are not available.
BTW, without having a conditional in there, the segue will be fired (and load the view controller) every time the view is loaded!
I am working on a project that does exactly what you want to do. Perform segue with identifier is the right thing to do. My project also does the check in viewDidLoad.
All your steps look fine, so I believe it's a subtle issue. Check the identity inspector to see if you connected the view controller with view 1
I have the following setup in my app:
My initial view controller is a UITabBarController.
the tabs:
1)UINavigationController->PostListVC
2)UINavigationController->CategoriesListVC
3)UINavigationController->PostListVC
4)UINavigationController->PostListVC
5)UINavigationController->MoreViewController
As you can see, 3 tabs contain the same viewController class, but should not contain the same view controller object - the view will display different information based on information he gets form the AppDelegate.
What I did is I created 5 UINavigationControllers, connected them to the uitabbarcontroller, then created a rootViewController segue for 3 of them to the same PostListVC View - that way I don't need to maintain 3 designs of the same view.
The problem that I get is that only the first PostListVC gets created properly ( the leftmost in the tab bar ) - the other tabs that point to a PostListVC just show a black screen.
I've tried to illustrate the way I wire-up the storyboard using a 3-tab example:
As you can see, both the upper-most and lower-most views are connected to PostListVC.
I do not know what the issue is. I assume I'm using storyboards somewhat wrongly.
Does anybody know how I can fix this?
Thanks!
EDIT:
I have created a simple, example project (Xcode 5) that illustartes this issue:
http://www.speedyshare.com/Srwfg/TabBarProblem.zip
EDIT 2:
A modified version of the example, showing the problem with the offered solution:
http://speedy.sh/JkdGC/TabBarProblem-2.zip
There is no way to create different tabBarItems with this method, and there's no way to place the barItems so that they're not in a row - even if you try to chagne the order of segues.
As you said you need three different instances of PostListVC then you should create three different viewcontrollers of type PostListVC and connect each tab to its own. The class is the same but each tab gets its own instance.
I have got your example program to work BUT I don't know if the solution will work for your full project. Hopefully, it will put you on the correct track.
The solution is to have ONE (1) Navigation Controller / embedded root view but TWO (2) segues from the Tab Bar Controller. Here's the picture:
It looks like there's a problem with multiple UINavigationControllers linking to the same UIViewController. But no problem with the same UINavigationController linking to the same UIViewController provided they are instantiated separately through the UITabBarController.
I just came across a slide-in menu I really like: https://github.com/uzysjung/UzysSlideMenu
I would like to use this menu for an application that uses several view controllers (UIViewControllers and UINavigationControllers).
In Xcode, I created a single view application and made the view controller (MenuViewController) show the menu, like the creator did in his example project. I added more view controllers to the storyboard and connected them via segues to the MenuViewController. Upon selecting a menu item, these segues are triggered and the selected view is shown - so far so good.
But now, I run into the following problem:
All my view controllers are shown in full screen. That means that VCs that get segue'd in the viewport don't show the menu, because it's just not implemented there. I could put the menu in every VC, but that doesn't seem to be the right way to do it (even if I use some custom delegate method that every controller calls, like putMenuInViewController:(UIViewController *)target). I think I need something like a global singleton for the menu and make it appear in every view controller, but I have absolutely no idea on how to it or what to google for.
Any points into the right direction are greatly appreciated :)
I think you need to implement one root view controller with this menu as singleton, and add other view controller as child view controller to it.
I wrote a post about it, you can find it here:http://antrix1989.blogspot.com/2013/09/uiviewcontroller-as-singleton.html
Situation: two UITabBarController's, each with their own tabs, but last tab in both is identical so want one UIViewController to show content.
Issue at runtime: Shared item only appears in one of the tab sets when shown.
Question: anyone know a way to make this work?
Link to external graphic of storyboard setup: (sorry, don't have enough reputation to post images here!)
Storyboard graphic
An Xcode project with that storyboard:
XCode Project
Each tab content item has it's own UIViewController class. They contain no code except the line to make the back buttons work.
(Yes, I know this is odd. Real situation is an iPad app where tab controllers are shown in popovers; popovers are "property editors" where different objects have different properties, but all share a common set of properties... thus one tab for "unique" props, one shared tab content for the "common" props all objects have.)
I've found a couple ways around this to get the effect I want, but if this storyboard worked it would be a much easier solution.
-- Other info, somewhat unrelated to question --
Alternate solution I'm using: TabBarControllers only link to one VC as tab content. When that tab VC loads, I use code to (a) instantiate shared VC from storyboard by identifier, (b) add that new VC object to the TabBarController via [tabController setViewControllers:list animated:NO].
(Another possible solution I like even less: not using a TabBarController, and presenting content VC's with my own "tab" graphic drawn into them, each showing "myself" as selected. Yuk.)
So I have a working solution, I'm just curious as to why this doesn't work (just a known thing in iOS API, or some magical property setting that might render it functional?)
You can't put the same view controller instance into two tab controllers. The problem is that a view (UIView) instance can only have one parent view (superview). When you try to add the view controller to the 2nd tab, the view controller's view gets removed from its first parent (the first tab) and then added to the 2nd tab.
I stumbled upon your thread while running into the same issue today...
The solution is to just make a duplicate of the view controller in story board and attach the duplicate to the other tab bar controller.
I just did it and it works...
I think the 'rdelmar' is right about this... copy it and set it ..!!
I ran across this same issue today. I managed to come up with a workaround that seems to do the trick. The key is to add a layer of separation between the tabbar and the controller you want to reuse. From each tabbar, I created a relationship to a distinct UIViewController with a container view. Then you can do an 'embed' segue from the container to the controller you actually want to reuse as the tab view. It is not quite as clean as a direct connection (not sure why that is not supported) since you do have to create a controller class for each reuse case. It is still a better solution than the nightmare of having to duplicate the actual tab view ( as well as any additional views that connect to it) for every use.
Hope this helps. Let me know if anyone needs more details.