EDIT: I was off base in my approach. I'm trying to pass data from one VC to another. The source VC is not controlled by a Tab Bar, so I can't reference the destination VC through it. I am attempting to reference the destination VC thorough the Storyboard, but the data is still nil on the destination VC. I'm using Core Data and wish to pass the ManagedObjectContext to another VC. Here is the code:
......
do {
try self.managedObjectContext.save()
appUserID = user.userID!
} catch {
fatalError("Error: \(error)")
}
}
}
self.passManagedObjectContext()
}
func passManagedObjectContext() {
let profileTableViewController = UIStoryboard(name: "Profile", bundle: nil).instantiateViewController(withIdentifier: "ProfileViewController") as! ProfileTableViewController
profileTableViewController.managedObjectContext = self.managedObjectContext
}
I am passing data from the AppDelegate to other ViewControllers by referencing my TabBarViewControllers stack like so:
let tabBarController = window!.rootViewController as! UITabBarController
if let tabBarViewControllers = tabBarController.viewControllers {
let profileNavController = tabBarViewControllers[4] as! UINavigationController
let profileTableViewController = profileNavController.topViewController as! ProfileTableViewController
profileTableViewController.managedObjectContext = context
}
}
.....
END EDIT
I'm trying to do the same now but from one ViewController to another that is accessed through the tab bar (no segue). The code above does not recognize window!.rootViewController how can I reference the root UITabBarController?
UIViewController has a built-in optional property tabBarController, so inside your view controller you can access the tabBarController like so:
if let tabBarController = tabBarController {
//get the controller you need from
//tabBarController.viewControllers
//and do whatever you need
}
Here is the current list of properties available in the 'Getting Other Related View Controllers' section of Apple's UIViewController documentation:
Related
I have a tabBarController with below hierarchy
TabBarController
Tab 1 -> Contains Navigation Controller(NavController1) -> ViewController1 -has--> ContainerView --contains--> DisplayedViewControllerTab1 (this is my tab1 view controller displayed)
Variable dataForVC1 is in DisplayedViewControllerTab1
When user taps Tab3 (DisplayedViewControllerTab3), I'm trying to get value of dataForVC1 to pass to tab3 viewController
So far I've tried this
In in TabBarController - didSelect method
var data: ModelData?
if let navController = tabBarController.viewControllers?[0] as? NavController1,
let childNavVC = navController.children.first as? ViewController1 {
//Get container view
let conView = childNavVC.containerView. //This is outlet
//Looking for something like this - struck here
if let displayedVC1 = "Container view's VC as? DisplayedViewControllerTab1 {
data = displayedVC1.dataForVC1
}
}
Kindly advice how to achieve this
You don't need to hustle around with container views. In your ViewController1 simply add references to the DisplayedViewControllerTab1 or other vc's you need and then access them directly.
Your VC code would look something like this.
class ViewController1: UIViewController {
//...
var displayedVC1: DisplayedViewControllerTab1?
//...
}
And then your code now:
var data: ModelData?
if let navController = tabBarController.viewControllers?[0] as? NavController1,
let childNavVC = navController.children.first as? ViewController1 {
data = childNavVC.displayedVc1
}
P.S. For convenience, if you have your own TabBarController class you can add all the references you need when the controller is created or simply have computed properties, so you don't need to go deep in the hierarchy all the time.
In your TabbarViewController class:
var myViewController1: MyViewControllerOne? {
return (viewControllers[0] as? NavController)?.children.first as? MyViewControllerOne
}
var myViewController2: MyViewControllerTwo? {
return (viewControllers[1] as? NavController)?.children.first as? MyViewControllerTwo
}
I have a mainviewcontroller and a popup view controller which opens without a segue.
the popup viewcontroller recive data from Firebase, and then i need to append this data to an array in the mainviewcontroller.
How can i do that?
(i tried to create a property of the popupviewcontroller in the mainviewcontroller, but in crashes the app)
this is the code that opens the popup:
#IBAction func showPopUp(_ sender: Any) {
let popOverVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "sbPopUp") as! PopUpViewController
self.addChild(popOverVC)
popOverVC.view.frame = self.view.frame
self.view.addSubview(popOverVC.view)
popOverVC.didMove(toParent: self)
You need to connect the classes so that the popup class knows what to do with the data once it has been received. Here's a sample structure that works in a playground that you should be able to apply to your real classes.
class MainClass {
func showPopUp() {
let popOverVC = PopUpClass()
popOverVC.update = addToArray
popOverVC.receivedData()
}
func addToArray() {
print("Adding")
}
}
class PopUpClass {
var update: (()->())?
func receivedData() {
if let updateFunction = update {
updateFunction()
}
}
}
let main = MainClass()
main.showPopUp()
Or you could create a global variable so it can be accessed anywhere. ... It is better to pass data but I just thought it would be easier in this instance, so the variable can be accessed anywhere in your entire project.
if it is just a notification, you can show it in an alert, but if you don't want to use an alert my offer to present another view controller is not like this , try my code :
//if you have navigation controller ->
let vc = self.storyboard?.instantiateViewController(
withIdentifier: "storyboadrID") as! yourViewController
self.navigationController?.pushViewController(vc, animated: true)
//if you don't use navigation controller ->
let VC1 = self.storyboard!.instantiateViewController(withIdentifier: "storyboadrID") as! yourViewController
self.present(VC1, animated:true, completion: nil)
also if you want to pass any data or parameter to destination view controller you can put it like this before presenting your view controller :
VC1.textView.text = "test"
enter image description hereAs per the screenshots, I was trying to set a UITabBarController as my root view controller. In the storyboard, a UITabBarController is my initial VC, however I get this issue.
I check the storyboard if the tab bar controller is my initial view controller, and if I messed up with unwrapping anything.
let tabController = window!.rootViewController as! UITabBarController
if let tabViewControllers = tabController.viewControllers {
let navController = tabViewControllers[0] as! UINavigationController
let controller = navController.viewControllers.first as! CurrentLocationViewController
controller.managedObjectContext = managedObjectContext
}
return true
}
expected: To run smoothly
actually result: the app launches, crashes on the launch. and I get the following error:
THREAD ONE FATAL ERROR: Unexpectedly found nil while unwrapping optional.
That line is crashing because either window is nil or the view controller is not a UITabBarController. If you remove the code inside didFinishLaunchingWithOptions does your app load without crashing and display the view controller you are expecting?
If so, maybe try moving the code to set the managed object context inside CurrentLocationViewController's viewDidLoad method:
let appDelegate = UIApplication.shared.delegate as! AppDelegate
managedObjectContext = appDelegate.managedObjectContext
If the app still crashes or does not display the tabbed view controller you are expecting, you might not have the initial view controller set up correctly.
Its an ugly way of doing it though...
to be super safe do this:
guard let tabController = window!.rootViewController as? UITabBarController else { return }
let viewControllers = tabControllers.viewControllers
if let navController = viewControllers.first as? UINavigationController {
if let controller = navController.viewControllers.first as? CurrentLocationViewController {
controller.managedObjectContext = managedObjectContext
}
}
In my Xcode project when a user taps on a notification I want to first send them to a certain item in my tabBar then I want to instantiate a view controller and send an object over to that view controller. I have code the that sends them to the tabBar I want, but I do not know how to instantiate them to the view controller while keeping the tabBar and navigation bar connected to the view controller. All the answers on this require you to change the root view controller and that makes me lose connection to my tabBar and navigation bar when the view controller is called.
A Real Life Example of this: User receives Instagram notification saying "John started following you" -> user taps on notification -> Instagram opens and shows notifications tab -> quickly send user to "John" profile and when the user presses the back button, it sends them back to the notification tab
Should know: The reason why I'm going to a certain tab first is to get that tab's navigation controller because the view controller I'm going to does not have one.
Here's my working code on sending the user to "notifications" tab (I added comments to act like the Instagram example for better understanding):
if let tabbarController = self.window!.rootViewController as? UITabBarController {
tabbarController.selectedViewController = tabbarController.viewControllers?[3] //goes to notifications tab
if type == "follow" { //someone started following current user
//send to user's profile and send the user's id so the app can find all the information of the user
}
}
First of all, you'll to insatiate a TabBarController:
let storyboard = UIStoryboard.init(name: "YourStoryboardName", bundle: nil)
let tabBarController = storyboard.instantiateViewController(withIdentifier: "YourTabBarController") as! UITabBarController
And then insatiate all of the viewControllers of TabBarController. If your viewControllers is embedded in to the UINavigationController? If so, you'll to insatiate a Navigation Controller instead:
let first = storyboard.instantiateViewiController(withIdentifier: "YourFirstNavigationController") as! UINavigationController
let second = storyboard.instantiateViewiController(withIdentifier: "YourSecondNavigationController") as! UINavigationController
let third = storyboard.instantiateViewiController(withIdentifier: "YourThirdNavigationController") as! UINavigationController
Also you should instantiate your desired ViewController too:
let desiredVC = storyboard.instantiateViewController(withIdentifier: "desiredVC") as! ExampleDesiredViewController
Make all of the NavigationControllers as viewControllers of TabBarController:
tabBarController.viewControllers = [first, second, third]
And check: It's about your choice.
if tabBarController.selectedViewController == first {
// Option 1: If you want to present
first.present(desiredVC, animated: true, completion: nil)
// Option 2: If you want to push
first.pushViewController(desiredVC, animated. true)
}
Make tabBarController as a rootViewController:
self.window = UIWindow.init(frame: UIScreen.main.bounds)
self.window?.rootViewController = tabBarController
self.window?.makeKeyAndVisible()
Finally: It's your completed code:
func openViewController() {
let storyboard = UIStoryboard.init(name: "YourStoryboardName", bundle: nil)
let tabBarController = storyboard.instantiateViewController(withIdentifier: "YourTabBarController") as! UITabBarController
let first = storyboard.instantiateViewiController(withIdentifier: "YourFirstNavigationController") as! UINavigationController
let second = storyboard.instantiateViewiController(withIdentifier: "YourSecondNavigationController") as! UINavigationController
let third = storyboard.instantiateViewiController(withIdentifier: "YourThirdNavigationController") as! UINavigationController
let desiredVC = storyboard.instantiateViewController(withIdentifier: "desiredVC") as! ExampleDesiredViewController
tabBarController.viewControllers = [first, second, third]
if tabBarController.selectedViewController == first {
// Option 1: If you want to present
first.present(desiredVC, animated: true, completion: nil)
// Option 2: If you want to push
first.pushViewController(desiredVC, animated. true)
}
self.window = UIWindow.init(frame: UIScreen.main.bounds)
self.window?.rootViewController = tabBarController
self.window?.makeKeyAndVisible()
}
If you want to present or push ViewController when the notification is tapped? Try something like that:
extension AppDelegate: UNUserNotificationCenterDelegate {
func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: #escaping () -> Void) {
switch response.actionIdentifier {
case UNNotificationDefaultActionIdentifier:
openViewController()
completionHandler()
default:
break;
}
}
}
I can think of two ways to do that:
1) If that view controller is a UINavigationController you can simply push the profile from wherever you are:
if let tabNavigationController = tabbarController.viewControllers?[3] as? UINavigationController {
tabbarController.selectedViewController = tabNavigationController
let profileViewController = ProfileViewController(...)
// ... set up the profile by setting the user id or whatever you need to do ...
tabNavigationController.push(profileViewController, animated: true) // animated or not, your choice ;)
}
2) Alternatively, what I like to do is control such things directly from my view controller subclass (in this case, PostListViewController). I have this helper method in a swift file that I include in all of my projects:
extension UIViewController {
var containedViewController: UIViewController {
if let navController = self as? UINavigationController, let first = navController.viewControllers.first {
return first
}
return self
}
}
Then I would do this to push the new view controller:
if let tabViewController = tabbarController.selectedViewController {
tabbarController.selectedViewController = tabViewController
if let postListViewController = tabViewController.containedViewController as? PostListViewController {
postListViewController.goToProfile(for: user) // you need to get the user reference from somewhere first
}
}
In my last live project, I'm using the same approach like yours. So even though I doubt this method is the correct or ideal for handling a push notification from the AppDelegate (I still got a lot of stuff to learn in iOS 🙂), I'm still sharing it because it worked for me and well I believe the code is still readable and quite clean.
The key is to know the levels or stacks of your screens. The what are childViewControllers, the topMost screen, the one the is in the bottom, etc...
Then if you're now ready to push to a certain screen, you would need of course the navigationController of the current screen you're in.
For instance, this code block is from my project's AppDelegate:
func handleDeeplinkedJobId(_ jobIdInt: Int) {
// Check if user is in Auth or in Jobs
if let currentRootViewController = UIApplication.shared.keyWindow!.rootViewController,
let presentedViewController = currentRootViewController.presentedViewController {
if presentedViewController is BaseTabBarController {
if let baseTabBarController = presentedViewController as? BaseTabBarController,
let tabIndex = TabIndex(rawValue: baseTabBarController.selectedIndex) {
switch tabIndex {
case .jobsTab:
....
....
if let jobsTabNavCon = baseTabBarController.viewControllers?.first,
let firstScreen = jobsTabNavCon.childViewControllers.first,
let topMostScreen = jobsTabNavCon.childViewControllers.last {
...
...
So as you can see, I know the hierarchy of the screens, and by using this knowledge as well as some patience in checking if I'm in the right screen by using breakpoints and printobject (po), I get the correct reference. Lastly, in the code above, I have the topMostScreen reference, and I can use that screen's navigationController to push to a new screen if I want to.
Hope this helps!
I am trying to init my core data stack with the init VC of my app. To do this I want to pass the core data manager i have created into the first VC upon loading.
I thought this code would make sense to pass the coredatamanager into the VC, however I get errors whichever way i write this code, im sure im missing something simple?
// Initialize Storyboard
let storyboard = UIStoryboard(name: "RoutineController", bundle: Bundle.main)
// Instantiate Initial View Controller
if let viewController = storyboard.instantiateInitialViewController() as? ViewController {
// Configure View Controller
viewController.coreDataManager = coreDataManager
// Set Root View Controller
window?.rootViewController = viewController
}
Error is simply:
Use of undeclared type 'ViewController'
However if i delete 'as? ViewController' I get an error on the following line that viewController has no property coreDataManager.
Is there some sort of delegate i need to define in the viewdidload of the view controller in sending to?
EDIT Revised my code to correct the storyboard ID, however the code inside the {} doesnt seem to execute, i get the printed error i wrote due to the if let failing, so this still isnt the right way to set the viewController...any ideas as to why?
// Initialize Storyboard
let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main)
// Instantiate Initial View Controller
if let viewController = storyboard.instantiateInitialViewController() as? RoutineController {
// Configure View Controller
print("SENDING THIS INFO TO THE FIRST VC \(self.coreDataManager)")
viewController.coreDataManager = self.coreDataManager
// Set Root View Controller
window?.rootViewController = viewController
} else {
print("WE COULDNT SET VIEWCONTROLLER AS THE DESIGNATED VC SO MOC WASNT PASSED")
}
This is your problem:
as? ViewController
should be
as! UIViewController
alternatively this should also work:
as! RoutineController
Select the RoutineController in your storyboard and set the storyboard ID
Then use the Storyboard ID here:
if let viewController = storyboard.instantiateViewController(withIdentifier: "<storyboardID>") as? RoutineController {
The solution was that you need to define an identifier in the if let viewController to find it successfully, the working code is as follows:
let storyboard = UIStoryboard(name: "Main", bundle: nil)
if let viewController = storyboard.instantiateViewController(withIdentifier: "TabBarController") as? TabBarController {
viewController.coreDataManager = self.coreDataManager
window?.rootViewController = viewController