I am trying to understand relationship between UINavigationController and UIViewController.
According to apple documentation
A container view controller that defines a stack-based scheme for navigating hierarchical content.
When I open UIKit and UINavigationController class there are some properties which I could not imagine, how they is written by Apple.
UINavigationController : UIViewController { }
so UINavigationController subclass of the UIViewController and inherit its properties.
then what about these properties in this extension ? These ones inherits from a protocol which I could not see in UIKit. Could you explain a little bit please ?
extension UIViewController {
open var navigationItem: UINavigationItem { get } // Created on-demand so that a view controller may customize its navigation appearance.
open var hidesBottomBarWhenPushed: Bool // If YES, then when this view controller is pushed into a controller hierarchy with a bottom bar (like a tab bar), the bottom bar will slide out. Default is NO.
open var navigationController: UINavigationController? { get } // If this view controller has been pushed onto a navigation controller, return it.
}
I am not sure what you need to understand but i will assume that it's why those properties are there and exposed for the UINavigationController.
As the definition address it UINavigationController is a basically a stack of UIViewControllers, that uses, push, pop functions to add and remove to the stack here is more about how stack works.
for the relationship, it's clear that's every UINavigationController is inheriting a UIViewController but it's tricky because you are thinking why? since it hold a UIViewController why it inherits from it the answer rely on the usage this allows us to have multiple navigations embedded in each others so a navigation controller can hold another navigation controller inside of it, that's why you see those properties so in a scenario you can have the following stack and those properties are there if you need to use them on the UINavigationController it self as it gets pushed.
let firstVC = UIViewController()
let secondVC = UIViewController()
let firstNav = UINavigationController(rootViewController: firstVC)
let secondNav = UINavigationController(rootViewController: secondVC)
firstNav.hidesBottomBarWhenPushed = true
let thirdNav = UINavigationController(rootViewController: firstNav)
thirdNav.pushViewController(secondNav, animated: false)
Related
Having some trouble permanently moving one from view controller to another. The normal segues seem to all have a 'go back' option.
I know I can imbed the VC in a navigation controller and create a custom segue which rewrites the hierarchy/changes root VC
class ReplaceSegue: UIStoryboardSegue {
override func perform() {
source.navigationController?.setViewControllers([self.destination], animated: false)
}
}
But I want to avoid a navigation controller as it will confuse things when I add a SWRevealViewController later.
Can/Should I change the storyboard VC (outside of AppDelegate that is)?
Thanks - apologies if this is a 'beginner' question
You can either change rootViewController of your main window:
self.window.rootViewController = vc
or you can just simply set vc's modalPresentationStyle to fullscreen (this doesn't have a "go back" option by itself, only you can dismiss it calling dismiss)
let vc = UIViewController()
vc.modalPresentationStyle = .fullScreen
or from storyboard change it's presentation style to fullscreen.
I have : navigation controller -> tableViewController -> tab bar Controller -> ViewController1 / ViewController2 / ViewController3
I click on a cell on the TableViewController and I open the TabBar. All is OK
But, I wanted to have more details from the datas in the TableViewController so I decided to make a popup with the content of the cell. I found this tutorial https://www.youtube.com/watch?v=S5i8n_bqblE => GREAT ! It's about the use of segue "present modally" with a viewcontroller containing the popup. I made a link from the popup to the tabBarController and I lose the Navigation Bar
I tried to play with navigationBar but nothing is working. I changed the type of segue but I don't obtain what I want.
I think the problem come from the type of segue. It's OK if I use it like a go/back in viewController. Do you have any solution about using this sort of popup or do I have to use another way ?
Thanks
Ok, let's take a look.
Navigation Bar is a view which is provided by Navigation Controller. Sometimes we are confused with navigation bars and navigation items. Navigation bar is the only one and it belongs to navigation controller, navigation item belongs to individual view controller from navigation stack. So, first step is simple: if you want navigation bar, wrap your modally presented controller into navigation stack.
Yes, you will face other problem, the blurred view of previous controller will become a black area. Why? there is special object called Presentation Controller (UIPresentationController) which is responsible for how controller will be presented. And it hides view of previous controller by default (in sake of performance, I think).
Ok, let's move. We can create custom presentation controller and tell it not to hide view of previous controller. Like this:
class CustomPresentationController: UIPresentationController {
override var shouldRemovePresentersView: Bool {
return false
}
}
Next step. In controller we want present modally we have to specify to things: we want to use custom presentation controller and we also want to adjust delegate object for transitioning (where we can specify custom presentation controller). The trick is that you have to do it inside initialiser, because viewDidLoad is too late: controller had been already initialised:
class PopupViewController: UIViewController {
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
modalPresentationStyle = .custom
transitioningDelegate = self
}
}
Final step. When PopupViewController became delegate for its own transitioning, it means this controller is responsible for all of them. In our particular case popup controller provides custom version of presentation controller. Like this:
extension PopupViewController: UIViewControllerTransitioningDelegate {
func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
return CustomPresentationController(presentedViewController: presented, presenting: presenting)
}
}
That's all. Now you should see view of previous controller.
I am proudly new to iOS developing and I am trying to build my first app. I am doing a course on an online platform which does the following in the
AppDelegate -> application didFinishLaunchingWithOptions:
let navigationController = window?.rootViewController as! UINavigationController
let notebooksListViewController = navigationController.topViewController as! NotebooksListViewController
notebooksListViewController.dataController = dataController
This app has a Navigation controller which begins with an UIViewController.
I have 2 questions here, first is why this works, I mean, I am in AppDelegate, so the NotebooksListViewController (first view of the app) is not instantiated yet (I think), so why I am able to inject a variable in it?
On the other hand, the second question, is how can I do this in a different scene? I have a TabBarViewController as first scene, and the first tab is a UITableViewController and I want to inject the same way my dataController var, how can I accomplish this? I could not get to do it, neither understand it.
Thanks in advance.
It works, because of some Xcode magic:
In your Target Setting, General tab, the Main Interface entry specifies the name of the Storyboard to be loaded automatically when your app starts up:
In the storyboard, the Initial View Controller then will be instantiated. It seems like this is an UINavigationController.
Since this is done automatically, it just works - until you want to do something special :-)
If you want to start up with a different scene - maybe from a different view controller - you could just change either the Main Interface to another storyboard, the Initial View Controller (inside the storyboard) or both.
Or, you could just start up by yourself, by leaving the Main Interface empty and create your own view controller inside the app delegate (didFinishLaunchingWithOptions), something like
self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
if let tabVC = mainStoryboard.instantiateViewControllerWithIdentifier("TabCtrl") as? UITabBarController {
self.window?.rootViewController = tabVC
// Access the subcontrollers, or create them
// Initialize their values
// tabVC.viewControllers[0].data = ...
} else {
// Ooops
}
self.window?.makeKeyAndVisible()
Answer to your first question
as the method name is self explanatory didFinishLaunchingWithOptions means your application is didfinish with launching with options and its about to enter in foreground so here application need to set rootViewController so in this method controller you want to set as view controller is initiated thats why you can inject variable in it
answer to second question
let navigationController = window?.rootViewController as! UITabbarController
let VC = navigationController.childViewController
//Now Using VC you can access all you controller of tabbar controller
let notebooksListViewController = navigationController.topViewController as!
NotebooksListViewController
notebooksListViewController.dataController = dataController
now as shown above you can use VC to access you view controllers
but be careful here because VC return viewcontroller array so you need make checks for perticular VC you want to access
I have implemented SWRevealViewController class for revealing a rear (left and/or right) view controller behind a front controller. SWRevealViewController of type UIViewController is the entry point in the app.
What do I want?
In class AppDelegate when applicationDidEnterBackground is called, I want to pop all the view controllers on the stack except the root view controller and updates the display.
What I tried?
if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
appDelegate.window?.rootViewController?.dismiss(animated: true, completion: nil)
}
I know that if SWRevealViewController were embedded in a UINavigationController, I could simply do (appDelegate.window?.rootViewController as? UINavigationController)?.popToRootViewController(animated: true) , but it is not embedded in nav controller and if I embed it, then I will not get the same behaviour, so how can I sort this out?
I believe what you are trying to do is an "unwindSegue".
They are are documented in a technical note:
https://developer.apple.com/library/content/technotes/tn2298/_index.html
With that you should be able to identify your root view controller as the target of the unwind segue and, of needed, follow the unwind through various steps as it occurs.
You can also look at the documentation for the various methods of UIViewController that contain the term "unwind"
https://developer.apple.com/documentation/uikit/uiviewcontroller
Try This:
let navVC = ((UIApplication.shared.delegate as? AppDelegate)?.window)?.rootViewController as? UINavigationController
for VC: UIViewController in (navVC?.viewControllers)! {
if (VC is MYViewController) {
navVC?.popToViewController(VC, animated: true)
break
}
}
I'm having a UISplitViewController that contains a UITabBarController as master view.
This UITabBarController contains a UINavigationController. The detail view contains a UINavigationController as well.
On the iPad this works as expected. The show detail segue presents the imageview within the navigation controller on the detail view.
On the iPhone on the other hand I expected that the show detail segue pushes the detail view on the stack of the navigation controller of the master view. But actually it is presented modally over the master view.
When removing the UITabBarController from the storyboard and using the UINavigationController directly in the master view this works.
Has anybody an idea how I could present the detail view on the stack of the master's UINavigationController on an iPhone?
The problem with Peter's solution is that it will fall apart with the iPhone 6 +. How so? With that code, if an iPhone 6 + is in portrait orientation - the detail view pushes onto the navigation stack. All is well, so far. Now, rotate into landscape, and then you'll have the detail view showing as the detail view and the master view.
You'll need the split view controller's delegate to implement two methods:
- (BOOL)splitViewController:(UISplitViewController *)splitViewController showDetailViewController:(UIViewController *)detailVC sender:(id)sender
{
UITabBarController *masterVC = splitViewController.viewControllers[0];
if (splitViewController.traitCollection.horizontalSizeClass == UIUserInterfaceSizeClassCompact)
[masterVC.selectedViewController showViewController:detailVC sender:sender];
else
[splitViewController setViewControllers:#[masterVC, detailVC]];
return YES;
}
And now, you'll need to return the top view controller from the selected tab's navigation controller:
- (UIViewController*)splitViewController:(UISplitViewController *)splitViewController separateSecondaryViewControllerFromPrimaryViewController:(UIViewController *)primaryViewController
{
UITabBarController *masterVC = splitViewController.viewControllers[0];
if ([(UINavigationController*)masterVC.selectedViewController viewControllers].count > 1)
return [(UINavigationController*)masterVC.selectedViewController popViewControllerAnimated:NO];
else
return nil; // Use the default implementation
}
With this solution, everything pushes onto the navigation stack when it should and also updates the detail view correctly on the iPad/6+ landscape.
I figured out how to put the detail on to the master's UINavigationController instead of presenting it modally over the UITabBarController.
Using the UISplitViewControllerDelegate method
- splitViewController:showDetailViewController:sender:
In case the UISplitViewController is collapsed get the masters navigation controller and push the detail view onto this navigation controller:
- (BOOL)splitViewController:(UISplitViewController *)splitViewController
showDetailViewController:(UIViewController *)vc
sender:(id)sender {
NSLog(#"UISplitViewController collapsed: %d", splitViewController.collapsed);
// TODO: add introspection
if (splitViewController.collapsed) {
UITabBarController *master = (UITabBarController *) splitViewController.viewControllers[0];
UINavigationController *masterNavigationController = (UINavigationController *)master.selectedViewController;
// push detail view on the navigation controller
//[masterNavigationController pushViewController:vc animated:YES];
// push was not always working (see discussion in answer below), use showViewController instead
[masterNavigationController showViewController:vc sender:sender];
return YES;
}
return NO;
}
The answer of #PeterOettl to his own question put me on the right way and is great for that. So the credit belongs to him.
I have nearly the same storyboard structure as him, but as vc is a navigationController I get a runtime error saying
'Pushing a navigation controller is not supported'
As said, that is because vc is the navigationController of the detail view and not the viewController of the detail view.
Note that I am surprised that #PeterOettl does not get that error in his case also, as the segue given in the storyboard picture, points to the navigation controller of the detail view.
Therefore the code should like that (in Swift) simply adding
let detailViewControllerNavigationController = (vc as UINavigationController).viewControllers[0] as UIViewController
and pushing detailViewControllerNavigationController instead of vc
and the whole code is
func splitViewController(splitViewController: UISplitViewController, showDetailViewController vc: UIViewController, sender: AnyObject?) -> Bool {
println("UISplitViewController collapsed: \(splitViewController.collapsed)")
if (splitViewController.collapsed) {
let master = splitViewController.viewControllers[0] as UITabBarController
let masterNavigationController = master.selectedViewController as UINavigationController
let detailViewControllerNavigationController = (vc as UINavigationController).viewControllers[0] as UIViewController
masterNavigationController.pushViewController(detailViewControllerNavigationController, animated: true)
return true
} else {
return false
}
}
Also note that this code is put in the AppDelegate.swift of the master-detail example of Xcode where a tab bar is added in the master view.
EDIT
In the comments we discussed with #PeterOettl of the difference between .pushViewController and .showViewController.
Apple documentation says :
showViewController:sender:
This method pushes a new view controller
onto the navigation stack in a similar way as the
pushViewController:animated: method. You can call this method directly
if you want but typically this method is called from elsewhere in the
view controller hierarchy when a new view controller needs to be
shown.
Available in iOS 8.0 and later.
I appreciate this discussion thread when I was implementing exactly the same UI structure app, and furthurmore made it adaptive for iPhone 6 Plus rotation and iPad multitasking (Slide Over/Split View, iOS 9 or later).
We have put the full solution (adaptive UISplitViewController with UITabBarController as primary view controller) open sourced on GitHub indievox-inc/TabBarSplitViewController. Thanks!
I implemented #Dreaming In Binary's answer in Swift:
func splitViewController(splitViewController: UISplitViewController, showDetailViewController vc: UIViewController, sender: AnyObject?) -> Bool {
let masterVC = splitViewController.viewControllers[0] as UITabBarController
if splitViewController.traitCollection.horizontalSizeClass == .Compact {
masterVC.selectedViewController?.showViewController(vc, sender: sender)
} else {
splitViewController.viewControllers = [masterVC, vc]
}
return true
}
func splitViewController(splitViewController: UISplitViewController, separateSecondaryViewControllerFromPrimaryViewController primaryViewController: UIViewController!) -> UIViewController? {
let masterVC = splitViewController.viewControllers[0] as UITabBarController
if let navController = masterVC.selectedViewController as? UINavigationController {
if navController.viewControllers.count > 1 {
return navController.popViewControllerAnimated(false)
}
}
return nil
}