My app has a TabBarController. Each tabBarItem relates to a ViewController embedded in a NavigationController.
When in first tabBarItem and selecting another tabBarItem I want to do some stuff before moving to the selected ViewController. Therefore I created a class for my tabBarController and made it UITabBarControllerDelegate.
What I want to do is present an alert with two buttons; button A cancels the move to the selected viewController and button B lets the move happen.
My problem is that when button B is pressed, I want to popToRootViewController. I gave the navigationController a storyboardID and tried to instantiate it like shown below.
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
if let alert = self.storyboard?.instantiateViewController(withIdentifier: "ActiveSessionWarningAlert") as? ActiveSessionWarningAlert {
alert.modalPresentationStyle = UIModalPresentationStyle.overCurrentContext
alert.modalTransitionStyle = UIModalTransitionStyle.flipHorizontal
let alertWasDismissed: (Bool) -> Void = { userWantsToMoveToSelectedViewController in
if userWantsToMoveToSelectedViewController {
if let navContr = self.storyboard?.instantiateViewController(withIdentifier: "firstNavContr") as? UINavigationController {
navContr.popToRootViewController(animated: true)
}
tabBarController.selectedViewController = viewController
}
}
alert.alertWasDismissed = alertWasDismissed
self.present(alert, animated: true, completion: nil)
}
return false
}
Everything works as expected, but the popToRootViewController doesn't seem to occur; when selecting the first tabBarItem again the same viewController that was 'active' when we left the item is still showing.
I checked so that the viewController I want to pop is actually in the navigation stack and that the navContr != nil.
What am I missing?
You don't say so, but I'm assuming that the alertWasDismissed closure you pass to your alert view controller gets invoked when the user dismisses the alert.
The problem with your closure is this bit:
if let navContr = self.storyboard?.instantiateViewController(withIdentifier: "firstNavContr") as? UINavigationController
Any time you call instantiateViewController(withIdentifier:), you are creating a brand new, never before seen instance of a view controller (a navigation controller in this case.) That navigation controller has nothing to do with the one that belongs to the current tab that you are trying to dismiss. It doesn't have anything in it's navigation stack other than the root view controller that is defined in the storyboard.
What you need to do is find the navigation controller of the current tab in your tab bar controller's tabBarController(_:shouldSelect:) method, and pass that navigation controller to your alertWasDismissed closure.
At the time the tabBarController(_:shouldSelect:) method is called, the tab bar controller's selectedViewController should contain the current view controller. Replace the line above with:
if let navContr = tabBarController.selectedViewController? as? UINavigationController {}
That should work.
Related
In my project you can create a post from a modal view.
When the modal view is dismissed (user presses on save post) I want to switch the tab bar controller to the second tab (post feed screen).
This topic is similar to my problem. The only difference being this is presented from a modal view. I can't figure out how to implement it in my code (tab bar is nil)
Switch tab bar programmatically in Swift
I have added 3 images to make this issue clearer
code screenshot
console message
#objc func saveAction(sender: UIButton) {
print ("> save pressed")
print(presentingViewController?.tabBarController)
print(presentingViewController)
presentingViewController?.tabBarController?.selectedIndex = 1
dismiss(animated: true)
}
edit: sorry stack overflow doesn't allow me to add images yet
You can do this using delegate pattern. But if you prefer not to add a delegate for this, you can do as shown below;
You can switch the tabbar by changing the selectedIndex property of tabBarController
if let presenter = presentingViewController as? LibraryViewController {
presenter.tabBarController?.selectedIndex = 1
}
dismiss(animated: true)
If you are presenting the modal on navigation controller in tabbar, use:
if let tabBar = presentingViewController as? UITabBarController {
tabBar.selectedIndex = 1
}
dismiss(animated: true)
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 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 have two storyboard (Main and SB2)
I have one view controller in storyboard in Main and one in SB2
I perform
let SB2 = UIStoryboard(name: "SB2", bundle:nil)
let vc : UIViewController = self.SB2.instantiateViewControllerWithIdentifier("VC2")
self.showViewController(vc, sender: self)
After the second viewcontroller loads and this command is run, it prints nil:
print(self.navigationController) // prints nil
In SB2 (second storyboard) I clicked on the viewcontroller (VC2) and then clicked on Editor > Embed In > Navigation Controller. This placed a navigation controller with the storyboard and the root view controller is VC2. I triple checked this. The first sign of it being connected was the gray navigation bar on top. The second being that there is segue connecting the navigation controller to VC2 and the last place I could have checked is in the navigation controller utilities.
I am thinking that maybe I shouldn't transition from VC1 to VC2 directly but rather VC1 to NavigationController however I don't know how to do this or if its even possible.
I don't know when sb2 prints nil when in face a navigation controller is connected to it. Any help is appreciated.
You need to push the view controller (VC2) on to the navigation controller.
let SB2 = UIStoryboard(name: "SB2", bundle:nil)v
let nvc = SB2.instantiateViewControllerWithIdentifier("NVC") as! UINavigationController
let vc : UIViewController = self.SB2.instantiateViewControllerWithIdentifier("VC2")
nvc.pushViewController(vc, animated: true)
Then in your view controller try calling
self.navigationController
In your storyboard,
select the initial ViewController. With this view controller selected, choose the menu item
Editor -> Embed In -> Navigation Controller
I have VC1 which is a basic view controller, I then want to present VC2 which is inside a navigation controller. Whenever I present it, it doesn't display the navigation controller. I want this all done pragmatically. The code I have been using to present VC2 is:
func matchesPressed(sender: UIButton!) {
let matchesTVC: Matches = self.storyboard?.instantiateViewControllerWithIdentifier("Matches") as! Matches
self.presentViewController(matchesTVC, animated: true, completion: nil)
}
How do I present the navigation controller it is inside as well?
Is the navigation controller in the storyboard? If so, give it a storyboard ID and replace your matchesTVC stuff with the navigation controller.
If matches is a standalone view controller in the storyboard, you can do it in code like this:
let matchesTVC: Matches = self.storyboard?.instantiateViewControllerWithIdentifier("Matches") as! Matches
let navContr = UINavigationController(rootViewController:matchesTVC)
self.presentViewController(navContr, animated: true, completion: nil)
Instantiate the navigation controller that contains your view controller and present the navigation controller.