In a Swift 3 project using Xcode 8.3 and iOS 10.3, I get a navigation controller to push. The app runs with a navigation controller until I try to use it to push. All works until the last line which cause an app crash, fatal error: unexpectedly found nil while unwrapping an Optional value. I don't want to use the storyboard, the point of this question is how to accomplish this task without the storyboard.
App Delegate code
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
window = UIWindow(frame: UIScreen.main.bounds)
window?.makeKeyAndVisible()
window?.rootViewController = UINavigationController(rootViewController: MainViewController())
}
View Controller:
import UIKit
class MainViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
let navController = navigationController
let myProfileViewController = MyProfileViewController()
navController!.pushViewController(myProfileViewController, animated: true)
}
}
Move
let navController = navigationController
let myProfileViewController = MyProfileViewController()
navController!.pushViewController(myProfileViewController, animated: true)
from viewDidLoad to viewDidAppear.
In viewDidLoad there is no parent navigation controller set up and you should not start animations from there.
You can add navigation controller in storyboard,
in Storyboard click on MainViewController & from editor menu add navigation controller & push via navigation controller as below code.
let vc = self.storyboard?.instantiateViewController(withIdentifier: "MyProfileViewController") as! MyProfileViewController
self.navigationController?.pushViewController(vc, animated: true)
Make sure storyboard identifier is correct. & remove navigation controller code form AppDelegate class.
first give name to your navigation controller like this
then in your code initialise it like this
let nav = (UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "yourNavigation") as! UINavigationController);
nav.pushFrontViewController(MainViewController(), animated: true);
window?.rootViewController = nav
Related
Hi I have the following scenario:
|---> VC1----->|
VC_Home ->|---> VC2----->|------> VCm
|---> VC3----->|
VC1, VC2 and VC3 can go to the same ViewController (VCm)
How to navigate back to the correct Previous VC from VCm
if I start from VC1 and go to VCm, then Vcm will return to VC1.
So, the same for VC2 and VC3.
all VC1, VC2, VC3 dont embed with NavigationController.
will this be able to identify which is the previous page?
#IBAction func goBack(_ sender: Any){
navigationController?.popViewController(animated: true)
}
Please help.
Thanks
Add UINavigationController in your storyBoard
Add new UIViewController [which is VC_HOME] and link it with UINavigationController as root View Controller (ctrl + drag)
Give it an ID (right utilities view -> Identity Inspector -> StoryBoard ID -> Name it "myHome")
Add 3 button [go to vc1, go to vc2, go to vc3] and of course add #IBAction for each of them
Add 3 different UIViewController for vc1, vc2, vc3 and like step 3 give them IDs myVc1, myVc2, myVc3
Now for #IBAction go to vc1 add following code :
let view = storyboard!.instantiateViewController(withIdentifier: "myVc1")
navigationController?.pushViewController(view, animated: true)
for #IBAction go to vc2 add following code :
let view = storyboard!.instantiateViewController(withIdentifier: "myVc2")
navigationController?.pushViewController(view, animated: true)
for #IBAction go to vc3 add following code :
let view = storyboard!.instantiateViewController(withIdentifier: "myVc3")
navigationController?.pushViewController(view, animated: true)
Now for each view add button go to VC_M like steps above
for back to previous viewController [vc1, vc2, vc3] use this code :
navigationController?.popViewController(animated: true)
if you back to the root [VC_Home] use this : navigationController?.popToRootViewController(animated: true)
just dismiss you final view controller. add following to you back action in your final view controller.
dismiss(animated: true, completion: nil)
I want to open present uiviewcontroller from class that inherts from nsobject .how this work?
I tried this code
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let initialViewController = storyboard.instantiateViewController(withIdentifier: "LoginSignupVC")
self.present (initialViewController, animated: false, completion: nil)
In your code self.present wont work because you're inside a NSObject class.
So self refers to NSObject class.
NSObject class doesn't have a method present in it.
For presenting a view controller you must have a navigation controller as root.
Solution 1: So get the navigation controller using self.navigationController and present your view controller to it.
let initialViewController = self.storyboard!.instantiateViewControllerWithIdentifier("LoginSignupVC") as! ViewController
self.navigationController!.presentViewController(initialViewController, animated: true)
Solution 2: Create a navigationcontroller manually and present in it.
let initialViewController = self.storyboard!.instantiateViewControllerWithIdentifier("LoginSignupVC") as! ViewController
let navController = UINavigationController(rootViewController: initialViewController)
self.presentViewController(navController, animated:true, completion: nil)
Hi I'm trying to present UiSplitViewController from UiViewController. I'm doing some search in UiViewController and based on result I display UiSplitViewController. How can I do it programatically? So far I tried 3 methods after googling
1.self.performSegue(withIdentifier: "SearchComplete", sender: self)
2.self.present(PrimarySplitViewController(), animated: true, completion: nil)
3.let detailViewController = self.storyboard?.instantiateViewController(withIdentifier: "SplitView") as! UISplitViewController
self.splitViewController?.viewControllers[1] = detailViewController
None of the above methods have worked how can I solve this. Thank you.
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let viewController = mainStoryboard.instantiateViewController(withIdentifier: "SplitView") as! UISplitViewController
UIApplication.shared.keyWindow?.rootViewController = viewController
You have to set root view controller
I'm working on an existing application which uses the storyboard but I want to continue development without using the storyboard at all, or nib files.
The existing left menu is a UITableView which is not the root controller and does not have a navigation controller associated with it. I have created a UINavigationController in the app delegate and want to use this navigation controller to push a new controller. I am able to present a view controller but I want to use push in order to conform with the current UIX.
In the following code nothing happens because navigationController? returns nil.
Here is my new code in the app delegate.
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
var navController: UINavigationController?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
navController = UINavigationController()
self.window = UIWindow(frame: UIScreen.main.bounds)
self.window!.rootViewController = navController
self.window!.backgroundColor = .red
self.window!.makeKeyAndVisible()
let menuViewController = SideMenuViewController()
menuViewController.navController = navController
Then in my side menu controller:
import UIKit
class SideMenuViewController: UIViewController {
var navController: UINavigationController?
.......
let myViewController = myViewController()
self.navigationController?.pushViewController(myViewController, animated: true )
From the UIViewController documentation:
var navigation​Controller:​ UINavigation​Controller?
The nearest
ancestor in the view controller hierarchy that is a navigation
controller.
Which means when you call self.navigationController in a view controller you get the (nearest) navigation controller that self is embedded in. Apparently your menu controller is not embedded in the navigation controller hierarchy. Using your app delegate's navController member is one way to make this work. Then you can say in your menu view controller:
func menuItemFooSelected()
{
let navController = (UIApplication.shared.delegate as! AppDelegate).navController
let myViewController = myViewController()
navController?.pushViewController(myViewController, animated: true)
}
Alternatively (and probably preferably), when you set up your initial structure in your app delegate, inject the navigation controller into the side menu controller:
class MenuViewController: UIViewController
{
var navController: UINavigationController?
...
func menuItemFooSelected()
{
let myViewController = myViewController()
self.navController?.pushViewController(myViewController, animated: true)
}
}
In application(_:didFinishLaunchingWithOptions:)
...
let menuViewController = MenuViewController(...)
menuViewController.navController = navController
I have 2 view controllers on my storyboard: viewController1(it input point) and viewController2. After loading the application i want to automatic presenting viewController2 after viewController1.
How i can do that?
if you want to go to second viewcontroller you can add this code to you viewDidLoad method:
let secondViewController = self.storyboard?.instantiateViewController(withIdentifier: "yourIdentifier") as! secondViewController
self.navigationController?.pushViewController(secondViewController, animated: true)
remeber to add a identifier for the second viewcontroller in storyboard and chenge the identifier that you use with "yourIdentifier"
if you don't want a animation put the animated: true to false.
if you dont want to show the fist viewcontroller, go into you storyboard and click on the second viewcontroller, then in the right side on attributes inspector select the box int the image:
For change viewcontroller you have to embed the first viewcontroller with a navigation controller, if you don't know how to do it, just select the fisrt viewcontroller and do like the image, click in navigation controller
Have you tried to show it in func viewDidLoad() {} like:
override func viewDidLoad() {
// ...
self.present(viewController, animated: true, completion: nil)
}
If you want to straight up load a different view controller you can do this in your app delegate:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "put your identifier here")
self.window?.rootViewController = vc
return true
}