self.navigationController!.popViewControllerAnimated(true)
So in above line i am having confusion that why I am getting navigation controller instance in the current class. According to the storyboard, navigation controller is present outside this class, but how come are we accessing the navigation controller in the current class?
The current viewController is being managed by the navigationController.
You could think of it in a similar way to a parent / child relationship. The navigationController is somewhat functioning like the parent of the viewController.
That property provides a reference to the navigationController provided it exists. In the same way you can say view.superView to access the parent view that the current view is inside.
Related
I want to build a custom container controller that emulates the following toolbar-related behaviors of UINavigationController:
Manages a UIToolbar, populated with the items in the toolbarItems property of a designated one of its child view controllers.
Updates its toolbar whenever -setToolbarItems: is called on that child view controller.
Updates—and animates updates—to its toolbar whenever -setToolbarItems:animated: is called on that child view controller with animated set to YES/true.
What do I need to do in my custom container controller?
I could observe the appropriate child's toolbarItems property with KVO… but then I'd miss any -setToolbarItems:animated: messages.
Basically I'm wondering… how does UINavigationController do this? Can I do the same thing?
You can get an inspiration from a reverse engineered UINavigationController in Chameleon and Microsoft projects
Can any one explain when should we add a UIViewController as ChildViewController?
What is the benefits of adding it as ChildViewController instead of subView?
Please help me to understand the purpose of ChildViewController.
When you add a view controller as child view controller, the parent view controller will hold a strong pointer to the child view controller so it doesn't get released instantly. This does not automatically add child's view to parent's view. So you will have to call them both.
I only used it when I needed to create multiple view controllers to be inserted in another view controller and didn't need to directly access it.
its all about UI and code management if you are using subview to achieve what you want to implement inside your app you need to code for your view inside same viewcontrollers class but something interesting i found by creating childviewcontrollers.
empowered to work on a seprate viewcontroller will invoked along with its parent viewcontroller along with its seprate class.
infinite controllers that will be updated tapping a button.
Creation of childViewControllers can be achived by implementing containerView.
or you must have a look of this link hope its helpful to understand.
I haven't really seen any resource that gives a good and simple explanations on relationship among window, rootviewcontroller, childviewcontroller, navigationcontroller and how they piece together in iOS development. Anyone one knows how to put this in a easy-to-understand way or any online resource or book that does a good job in explaining it?
Per the documentation on UIWindow:
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIWindow_Class/
A UIWindow object provides the backdrop for your app’s user interface and provides important event-handling behaviors. Windows do not have any visual appearance of their own, but they are crucial to the presentation of your app’s views.
Xcode typically provides your application's main window, but you can add more if you need to.
From the documentation link you can see that UIWindow is actually a UIView
Enter your first view controller. Like providing a main window, when you start a new Project in Xcode the project template usually wires up your initial view controller, which as the name implies controls a view (UIView).
You could call this initial view controller your RootViewController but if you get a handle on the UIWindow you could just as easily swap out the current initial view controller's view for any other view controller view you like.
That probably doesn't help with hard and fast rules for things, but if I understand what you are asking, RootViewController is likely the initial view controller for you application. For example, if you are using Storyboards, Xcode typically makes Main.storyboard, you will see a gray arrow pointing to the UIViewController representation.
This is pointing to the Storyboards Initial View Controller. You can verify this from the Attributes Inspector. Select the view controller then select the attribute inspector:
So that's basically RootViewController. ChildViewController is just any other view controller that is a child of a view controller.
I assume what you are referring to is:
addChildViewController:
removeFromParentViewController
willMoveToParentViewController:
didMoveToParentViewController:
You can read more about these methods here:
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIViewController_Class/
Under Implementing a Container View Controller
The quick gist of it is, A View Controller controls a view. View's can have subviews. Those subviews can come from other View Controllers. The methods outlined above pretty much just enable things like viewWillAppear, or viewWillDiappear to be called on the child view controller automatically when those methods are invoked on the parent view controller.
Per the docs:
By default, rotation and appearance callbacks are automatically forwarded to children. You may optionally override the shouldAutomaticallyForwardRotationMethods and shouldAutomaticallyForwardAppearanceMethods methods to take control of this behavior yourself.
a NavigationController is just like any other View Controller. It contains some special behavior for transitioning between views, but like other View Controllers it has a View (UIView) that it manages. A navigation controller could be your Initial View Controller / RootViewController just as any other View Controller can be, it all just depends on what you are trying to do. For example, a simple app that is just a list view, where you can tap an item and get a detail view could be constructed as:
1) Initial View Controller -> NavigationController
2) The NavigationController's first ViewController (Apple calls this a RootViewController) would then be a TableViewController.
3) Selecting a TableCell in the TableView (TableViewController manages a TableView) would then transition you to your Detail View Controller. The Navigation Controller knows how to do all that Sliding back and forth drama.
That's a pretty simplistic overview you can search the internet/youtube for more full featured tutorials outlining the same thing in more detail.
Example: https://www.raywenderlich.com/113388/storyboards-tutorial-in-ios-9-part-1
It's worth your time to do a few of these to get your bearings. Yes, it will likely cost you a few hours of your day. Take heart, everyone who ever started doing iOS development had to go though the same thing. =)
If I have ViewController1 and do a Popover Presentation to ViewController2. How I can call methods of ViewController1 in ViewController2?
If a child view controller needs to call methods on its parent you might want to reconsider the design and investigate whether you can refactor- normally a view controller should be essentially self-contained and a child shouldn't need to know about its parent.
However, you can accomplish this by implementing prepareForSegue(segue, sender) in the parent view controller and setting appropriate properties on the child (accessed via segue.destinationViewController).
In my app i am using PageViewController which has two different View Controllers. I implemented that it works fine. Now what i am trying is to pass some information from MainView Controller to ChildView Controllers when bar button clicked. I tried using protocol,but it doesn't seems to be working.
MainViewController
import ViewControllerA
import ViewControllerB
#protocol MainControllerDelegate<NSObject>
-(void) passInformation :(NSString*)someInfo;
end
MainController<PageViewControllerDelegate>
In
ViewControllerA
What i would like to see is accessing the main controller delegate in child view controller and pass information when some action taken placed in main view controller navigation bar button.
ViewControllerA<MainControllerDelegate> // Can't find the delegate saying undefined
I am sure there will be a way to pass information between UIPageViewController and its Child View controllers. I tried a lot but couldn't find the answer.
Did you import the MainViewController.h file into your ViewControllerA file?
You haven't provided enough information. Post the whole header for both classes, indicating which one is the parent and which is the child. Post the code in the parent view controller that creates the child view controllers. The trick is when you instantiate a view controller that fills one of the pages in your page view controller, you need to set a property in the child that points the child view controller.
I've been working in Mac OS lately, so I'm a bit rusty on page view controllers. If I remember correctly, you pass them an array of the view controllers they manage.
You'd instantiate each of the child view controllers, set up pointers both ways, and then install them in the page view controller.