I have been looking around and I can't find any clear answers. How can I access methods and properties written in the TabBarController from a ViewController attached to it?
The TabBarController has ViewControllers A and B attached to it. VCA has VA1, and VCB has VC2 each connected by a segue. How can I allow VC1 to use methods and properties found on TabBarController.
In this case your tab bar controller can be accessed via parentViewController of child VCs, unless those are inside their own containers, like navigation VC, then you'll need to go up one level.
Related
I'm writing an app with two or three main features. So I use Tabbarcontroller to switch between viewcontrollers (VC). The problem is, if I switch from VC1 to VC2, and then switch back to VC1, content of VC1 has changed when it moves from background to the foreground.
Does it mean that this is a newly instantiated VC, different from the VC1?
If so, how can I keep VC1 and push it to the front without creating a new VC?
I'm trying to search for the solutions but I don't know which keyword to begin with.
Please help me. Thanks.
The default behavior of UITabBarController is to hold references to the tabs (the ViewControllers) in it´s viewControllers property. If you switch back and forth the viewDidAppear() method is called on the ViewController for the selected tab.
The controllers managed by a UITabBarController will be allocated while the TabController is allocated. After that it will use the same instances of the controllers.
You may update some UI in viewDidAppear?
For reference: UITabBarController
I have two UIViewControllers, vc1 and vc2.
I want to switch between them. But before loading the view of the new view controller, I want to destroy/release/remove (I'm not sure abt the correct word to use here) the previous viewcontroller.
For example, when I am switching to vc2 from vc1 ,I want to destroy vc1 completely, so that when I return to vc1 from vc2, vc1 will be loaded from scratch (i.e. viewDidLoad will be executed).
Which type of view switching should I opt for?
presentModal...
addSubview.
I am not using a navigation controller.
Currently I am using the presentModal... method, but when I use dismissModalViewcontroller on the newly presented view controller, it doesn't show up a new instance of the previous view controller. Instead, it shows the already running instance of it.
I want the viewDidLoad method of the previous view controller to run when I dismiss the newly presented view controller.
What exactly needs to happen in viewDidLoad?
You also have viewWillAppear available to you, so it could be that you could move the required functionality there and still use the modal presentation.
See this answer. You can do this with or without animation.
Animate change of view controllers without using navigation controller stack, subviews or modal controllers?
i´ve created a UINavigationController in my appdelegate and initialized it with my "modelselectionViewController". This VC has different uibuttons and when touched, a new VC ("modelViewController") is pushed on the navigationstack.
This "modelViewController" acts as my template view and has a uitabbarcontroller with different tabs. The first VC is shown immediately but any changes on the navigationcontroller doesn´t work. I would like to set the name of the title but that navigationcontroller is null.
NSLog(#"navi: %#",
self.navigationController);
If i change my code to push the different VC when touching the different tabs, navigation works but only with a third level of navigation hierachy.
I want to know if it´s possible to use only one navigationcontroller for all my different tabs. Hope i made my setup clear. Appreciate all your help. thanks
I think you might want to read Combining ViewControllers.
In general, you should have the tabbar controller as a 'root' controller, not as a 'child' controller. A quick search in Apple's doc didn't yield a formal 'forbidden', but it might be.
If you create a UITabBarController from a view that's managed in a UINavigationController (ie: if you create a navigationcontroller first, and it's still around when you create the tabbarcontroller), you're starting a fight with the frameworks. Here's the admonishment from the docs on combining viewcontroller interfaces:
An application that uses a tab bar
controller can also use navigation
controllers in one or more tabs. When
combining these two types of view
controller in the same user interface,
the tab bar controller always acts as
the wrapper for the navigation
controllers. You never want to push a
tab bar controller onto the navigation
stack of a navigation controller.
Doing so creates an unusual situation
whereby the tab bar appears only while
a specific view controller is at the
top of the navigation stack. Tab bars
are designed to be persistent, and so
this transient approach can be
confusing to users.
I read that as "if it doesn't break something that we haven't thought of on the next update, we might reject the app anyway because it's 'confusing to users.'"
I suppose you could kill the whole navigation hierarchy and the navigationcontroller if you don't need to return there (like if you just used it for a one-time setup screen). Or you can look into other options for navigating within a viewcontroller that's managed by the navigationcontroller.
One thing to try might be to navigate to a UITableView, and use its cells to push a modal view onto the navigation stack. That would be familiar to users and also jive with the intent of the navigation classes.
If I instantiate a lets say, UISegmentedControl. And link each button to add a viewcontrollers view to the viewhierachy, would it be enough to just add that view to the stack or must I call other methods aswell. And what about removing views? Would it be sufficient to just say
I do NOT have the correct syntax in front of me right now so bear with me.
[self removeSuperview];
Is it necassary to call methods on the viewcontroller itself?
Use a NavigationController and either push or present Modally the views. The you can just pop or dismiss them.
I have a Navigation Controller with a root table view which has several links. Tapping each link moves to the next view (by pushing it to the navigation controller's stack). But suppose that in that "next view", I have a UIButton that should take me further to another view (by pushing on to the same navigation controller's stack)...
View Controller-->first view-->second view-->third view..........
Now, I can easily access the Navigation Controller when I deal with the first view (and successfully push it to the Navigation Controller's stack) because it has been instantiated in the same file itself. What my real doubt is--How do you access a Navigation Controller in a far off view controller (eg, the third view or fourth view etc)? Please note that I am not using any separate delegate. All the Navigation Bar methods have been implemented in one file and connected to the Navigation Controller via an outlet.
When you push a ViewController onto a NavigationController the ViewController will automatically have it's navigationController property set. This means you can access the same NAvigationController no matter where you are in the stack.
-Update-
navigationController
In every UIViewController you can access that property.
So to in any other UIViewController that has been pushed onto the stack you should be able to just do this:
[self.navigationController pushViewController:othercontroller animated:YES];
Look at the documentation for UIViewController to see what other magic properties you have available.