In my app i am using tabbar controller with 5 tabs,in 3 tabs,when click on a button it calls one View Controller. I am using same view controller for those 3 tabs so i am getting problem while calling same view in different tabs,So while changing the tab i dont want to call ViewWillAppear method. So what i have do? or else how to find previous selected index of the tabbar controller?
Thanks in Advance
I think you are not familiar with iOS Development.
In a TabbarController we can specify as much of UIViewcontroller/UINavigationController object.
if we need to re-use a UIViewcontroller you need to tag the view controller using a property object.
You need to use different instance of UIViewController for different tab.
While Showing a UIViewController its viewWillAppear got fired. we don't able to remove this behavior. But in most case we can handle such case with viewDidLoad (It is called once for an instance of view controller).
if we need to track the previously selected tab item we need to do our own work-around by using a shared class or static variable.
thanks,
Naveen Shan
Related
Background
I am developing an application which contains a top nav bar with an icon that allows to go back to the main ViewController.
As there as several ViewControllers, I don't want to duplicate the segue on each ViewController. I would prefer to create a custom class for the top nav bar and be able to programmatically present the main ViewController. I found that I could maybe call present(viewControllerToPresent:animated:completion)
Questions
Is this the right way to do it?
How do I access the controller I need to pass to this function?
Is there a method which allows to get the controller from its title?
Also, as the main ViewController has already been instantiated when the application started, do I need to instantiate a new one or can I get a reference to the existing one?
So if I get this correct you click mainVC->firstVC->secondVC->nthVC and then you'd want to go directly back to mainVC ? View controllers are stacked so what I'd do is just dismiss all those view controllers that are above mainVC.
I'm trying to come up with something simple, but i can't figure it out.
I have a UITabBarController and at one point I have to display another tab's UIViewController, and call a method in that new UIViewController, using data from the original UIViewController.
So basically I want to pass data to another UIViewController (that may not be initialized yet), and show the right tab.
If I use NSNotificationCenter, I'm not sure if the tab's UIViewController is initialized yet, and also it's a bit ugly to use delegation here.
What is a clean way to send and show data in the new tab?
A better idea would be to have a protocol implemented in the tab view controller the view controller can call to send data and set up any other view controller
You should have a data model of some sort (singleton?) that is accessible by both view controllers. When the second view controller is about to display its view, it should reference the data model to determine the data it should display.
int x = 1; //this is the view controller you want to go to.
MySecondViewController *secondViewController = (MySecondViewController *)self.tabBarController.viewControllers[x];
[secondViewController setDataObject:dataObject];
[self.tabBarController setSelectedIndex:x];
So what's happening is you're calling the controller from the tabBarController, it will initiate there if its not. Then you can set whatever you want on the controller, then you just switch to the selected tab.
In the view controller that has a UITabBarItem, i realized that viewDidLoad() method only gets called the first time when the tab bar item is clicked. So I dont know how to bring up the dynamic graphics when it's clicked the 2nd time. Can some guru help me on this? thanks in advance.
Should I conform to some kind of delegates or should i do it within didSelectViewController method on the root controller of all the tab bars? If i do the later one, it just seems to be weird since i think the controller that has the corresponding tab bar item should render itself instead of doing the rendering on root controller..
You want to put any code that should run every time the view controller appears in viewWillAppear: instead of viewDidLoad. viewDidLoad is designed for code that should run when the view backed by your UIViewController is created (and then possibly re-created after being thrown away during low-memory situations).
Actually i resolved this by using the parameter passed into the callback didSelectViewController(param).
In iOS5 using storyboard feature I want to create a custom container which will have 2 ViewControllers embedded in it. For Example, embed Table view controller as well as a view controller both in one ViewController.
That is, one view controller will have 2 relationship:
to table view controller
to view controller which in turn will have 4 UIImage view Or UIButton in it
Is creating this type of relationship possible using storyboard's drag drop feature only & not programmatically?
,You should only have one view controller to control the scene. However, this viewController might have two other view controllers that control particular subviews on your scene. To do this you create properties in your scene viewController, in your case one for your tableViewController and one for your view. I like to keep things together so I make both these viewControllers outlets and create them in interface builder. To create them in interface builder pull in an Object from the Object library and set its type to the relevant viewController. Hook it up to the appropriate outlet you just created in your scene's viewController - Note: this is important otherwise the viewController will be released if you are using ARC and crash your app. Then hook these viewControllers up to the view you want them to control and you are done.
Alternatively you can instantiate and hop up your viewControllers in your scenes viewController should you prefer to do this.
Hope this helps.
Edit: On reflection this is not a good idea and actually goes against the HIG you should maintain only one ViewController for each screen of content and instead try to create a suitable view class and have the single view controller deal with the interactions between the various views.
There is a way to do it that isn't too hacky. It is described at the following URL for UITabBarControllers, which you could use the first view controller in the list control the first subview, and the second one control the other. Or, you can probably adapt the code to work with UISplitViewController.
http://bartlettpublishing.com/site/bartpub/blog/3/entry/351
Basically, it works by replacing the tabbarcontroller at runtime after iOS has finished configuring it.
If I want to replace one screen of an app with another, but I don't use a navbar/tabbar controller, then I could just remove oldViewController.view from window and add newViewController.view to it. That's all, now newViewController will get rotation events, etc.
But UIView does not reference "its" controller, so how is this possible, how iOS know it should make newViewController an active one? Does iOS do some magic, it internally references controller from view or what?
UPDATE:
I think I was misunderstood: I don't ask how to make some view controller an active one - I know that. I'm just curious, how is it possible that I pass some view to UIWindow object ([window addSubview:view]) and it somehow finds view controller although view doesn't know its controller.
yeh I had the same question like you. and I figured it out.
UIView is derived from UIResponder. and UIView must subclass UIResponder::nextResponder.
Its default implementation is returning a view controller of the view (if it hadn't, it would be super view)
So, consequently view can see its controller. that means window know the topmost view and also
its controller.
good luck.
Unfortunately, iOS only send events to the first ViewController of the stack. You can try and present a new one on the top of others with video for example, it will never rotate.
If you don't use navbar/tabbar controller you will have to add and remove everytime from the Window to keep only one at the time if you wand to have events.
The main UIWindow class for your application will have a view controller set in its rootViewController property. That controller's view is the "main" view for the app. This is usually setup in the main .xib for the project. That view controller will receive the usual events like "viewDidAppear" or "willRotateToInterfaceOrientation". You can put up your own view over top of it if you want to, but you will need to manage those events yourself. Usually you don't do that though. You just use a UINavigationController or UITabBarController as your rootViewController and allow them to manage getting the events to new "pushed" view controllers, or you popup view controllers with "presentModalViewController".