It seems that I lack the basics of swift, so I am studying from the beginning while watching YouTube.
youtube example : https://www.youtube.com/watch?v=vI7m5RTYNng
At 5:40~7:40 seconds of the video, I get an error in class ViewController: UIViewController where I change UIViewController to UIcollectionViewContorller,
But there is an error. There is an error in the video. I looked at it and followed the video exactly, but in the video the error was resolved and I did not. I think the code is the same, why doesn't the error get resolved?
Error name
[UICollectionViewController loadView] instantiated view controller with identifier "UIViewController-BYZ-38-t0r" from storyboard "Main", but didn't get a UICollectionView.'
I thought it was an error because I didn't create anything on the storyboard, but there was nothing on the storyboard in the video.
ViewController
import UIKit
class ViewController: UICollectionViewController {
override func viewDidLoad() {
super.viewDidLoad()
collectionView.backgroundColor = .yellow
}
}
AppDelegate
import UIKit
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
let layout = UICollectionViewFlowLayout()
window?.rootViewController = ViewController(collectionViewLayout: layout)
return true
}
// MARK: UISceneSession Lifecycle
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
}
I searched hard, but I don't understand well because I lack basic knowledge about swift.
Thank you
It seems like you are using Xcode 11+. The video is kind of outdated now, as it's using Xcode 10 or before. Since Xcode 11, the App project template will create a SceneDelegate.swift for you. You should set the rootVC of the window in the SceneDelegate instead:
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
guard let _ = (scene as? UIWindowScene) else { return }
let layout = UICollectionViewFlowLayout()
window?.rootViewController = ViewController(collectionViewLayout: layout)
}
...
Here, the window variable will be assigned by UIKit the actual UIWindow instance. On the other hand, the window in AppDelegate.swift, which you probably declared yourself (after Xcode 11 they moved the window property from AppDelegate to SceneDelegate), doesn't get this special treatment.
Related
My app supports older versions of iOS 10.0 and above. When I try to launch my app in iOS 13, it shows a black window. It does configure initial ViewController and shows labels when I remove the scene delegate. Everything works in iOS 12 and under with just App delegate.
In my App delegate:
#main
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
configureInitialViewController()
return true
}
func configureInitialViewController()
{
var initialVC: UIViewController
let mainsb = UIStoryboard(name: "Main", bundle: nil)
if Auth.auth().currentUser != nil {
//print("successfully signed in")
initialVC = mainsb.instantiateViewController(withIdentifier: IDENTIFIER_MAIN_TABBAR)
} else {
//print("successfully signed out")
initialVC = mainsb.instantiateViewController(withIdentifier: IDENTIFIER_WELCOME_NAV)
}
window?.rootViewController = initialVC
window?.makeKeyAndVisible()
}
func applicationWillResignActive(_ application: UIApplication) {
Api.User.isOnline(bool: false)
}
// MARK: UISceneSession Lifecycle
#available(iOS 13.0, *)
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
#available(iOS 13.0, *)
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
}
In my Scene delegate:
#available(iOS 13.0, *)
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
guard let _ = (scene as? UIWindowScene) else { return }
}
func sceneWillResignActive(_ scene: UIScene) {
Api.User.isOnline(bool: false)
}
}
I also deleted Application Scene Manifest in my info.plist.
Can someone help me check if I'm setting up version supports correctly?
I would really appreciate any help.
Update:
I tested it works in iOS 13.5 but not 13.2 or 14.3. Why is it showing different behaviors in different versions?
In your AppDelegate inside didFinishLaunchingWithOptions add this:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
if #available(iOS 13.0, *){}
else{
//Load your vc
}
return true
}
Then in your SceneDelegate inside willConnectTo add these:
#available(iOS 13.0, *)
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
guard let _ = (scene as? UIWindowScene) else { return }
guard let windowScene = (scene as? UIWindowScene) else {return}
let window:UIWindow = UIWindow(windowScene: windowScene)
self.window = window
self.window?.rootViewController = // set you VC
self.window?.makeKeyAndVisible()
}
After reading https://medium.com/ios-os-x-development/ios-start-an-app-without-storyboard-5f57e3251a25
I have performed the following steps
Remove Main.storyboard and LaunchScreen.storyboard from the project
Remove Main from Main Interface under Deployment Info
Remove reference to Main.storyboard and LaunchScreen.storyboard from Info.plist
Here's some screenshots of the above steps
In AppDelegate.swift, I have make the following modification
import UIKit
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
window = UIWindow(frame: UIScreen.main.bounds)
let viewController = ViewController()
viewController.view.backgroundColor = UIColor.red
window!.rootViewController = viewController
window!.makeKeyAndVisible()
print("application executed")
return true
}
}
When I launch the simulator, the "application executed" is printed at console.
I am expecting to see a full screen red color once the app launched. However, I only can see an entire black screen.
May I know what else steps I have missed out?
You have scene life-cycle, so window should be created in SceneDelegate.
Here is AppDelegate:
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
return true
}
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
}
and now here is SceneDelegate
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
if let windowScene = scene as? UIWindowScene {
let viewController = ViewController()
viewController.view.backgroundColor = UIColor.red
let window = UIWindow(windowScene: windowScene)
window.rootViewController = viewController
self.window = window
window.makeKeyAndVisible()
}
}
}
Hello I was wondering if there is a way or how to make a tabBarControllerView once the user logs in programmatically without using storyboard. After doing research I found out how to do it by setting in the appDelegate the tabBarViewcontroller class as rootview. But my root view is the login screen. I was wondering if there was a way to do create a tabBarView and load it once the app reaches a certain ViewController/screen.
Here is my tabBarViewController class so far:
import Foundation
import UIKit
class tabBarControllerView: UITabBarController{
override func viewDidLoad() {
super.viewDidLoad()
UINavigationBar.appearance().prefersLargeTitles = true
viewControllers =
[UserProfileControllerUIKIT(),MainPageUIKIT(),OtherPageUIKit()]
}
}
Here is my appDelegate:
//
import UIKit
import Firebase
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions:
[UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
FirebaseApp.configure()
window = UIWindow()
window?.makeKeyAndVisible()
window?.rootViewController = tabBarControllerView()
return true
}
// MARK: UISceneSession Lifecycle
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
}
You can change rootviewcontroller after login
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.window?.rootViewController = tabBarControllerView()
appDelegate.window?.makeKeyAndVisible()
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
if let navController = window.rootViewController as? UINavigationController,
let personController = navController.controllers[0] as? PeopleTableViewController{
print("something")
}
return true
}
But it is giving me an error, it is not recognizing the window property of the AppDelegate, did they change with IOS 13 because it works in my IOS 12 project
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
lazy var persistentContainer: NSPersistentContainer = {
let container = NSPersistentContainer(name: "DataModel")
container.loadPersistentStores { description, error in
if let error = error {
fatalError("Unable to load persistent stores: \(error)")
}
}
return container
}()
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
if let navController = window?.rootViewController as? UINavigationController,
let personController = navController.viewControllers[0] as? PeopleTableViewController{
personController.persistentContainer = persistentContainer
print("Nailed it ")
} else {
print("Sorry")
}
return true
}
// MARK: UISceneSession Lifecycle
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
func applicationWillTerminate(_ application: UIApplication) {
persistentContainer.saveContextIfNeeded()
}
}
This is how my AppDelegate class looks
Here is how you set App's initialView Controller/rootViewController inside Scene Delegate class (this class handles Application Lifecycle Methods which were earlier handled by AppDelegate).
import UIKit
import SwiftUI
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
let initialViewController = UIStoryboard(name: "Storyboard", bundle: nil).instantiateViewController(identifier: "DatePicker") as! DatePicker
let navigation = UINavigationController(rootViewController: initialViewController)
// Use a UIHostingController as window root view controller.
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = tabBarCnt
self.window = window
window.makeKeyAndVisible()
}
}
func sceneDidDisconnect(_ scene: UIScene) {
// Called as the scene is being released by the system.
// This occurs shortly after the scene enters the background, or when its session is discarded.
// Release any resources associated with this scene that can be re-created the next time the scene connects.
// The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
}
func sceneDidBecomeActive(_ scene: UIScene) {
// Called when the scene has moved from an inactive state to an active state.
// Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
}
func sceneWillResignActive(_ scene: UIScene) {
// Called when the scene will move from an active state to an inactive state.
// This may occur due to temporary interruptions (ex. an incoming phone call).
}
func sceneWillEnterForeground(_ scene: UIScene) {
// Called as the scene transitions from the background to the foreground.
// Use this method to undo the changes made on entering the background.
}
func sceneDidEnterBackground(_ scene: UIScene) {
// Called as the scene transitions from the foreground to the background.
// Use this method to save data, release shared resources, and store enough scene-specific state information
// to restore the scene back to its current state.
print("App entered Background")
}
}
I found out a way around. instead of putting your code in didFinsishLoadingWithOptions method, getting the UIview comptroller's persistentContainer variable and then passing the persistentContainer in AppDelegate. you can just add this to the top of the view Controller.
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.context
if you want the appDelegate you can access like this
let AppDelegate = UIApplication.shared.delegate as! AppDelegate
This works both IOS12 and IOS13 so, you don't have to change your code
This question already has answers here:
Why is manually setup root view controller showing black screen?
(3 answers)
Closed 3 years ago.
I want to initialize window inside appDelegate to show specific ViewController depend on some cases. Now I have this code:
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
window = UIWindow()
let rootNavigationController = UIViewController()
window?.rootViewController = rootNavigationController
window?.rootViewController?.view.backgroundColor = .green
window?.makeKeyAndVisible()
return true
}
// MARK: UISceneSession Lifecycle
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
}
I'm using XCode11 and have created new project. SceneDelegate file I removed cause it hasn't effect on this. Also removed Main from Info.plist and from deployment info
As result on device I see black screen but debugger show me that rootNavigationController as should be
image from debugger
How fix it or implement this logic for XCode11?
Solution:
1)Inside manifest(plist) file remove Storyboard Name field
2)inside SceneDelegate.swift implement:
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
guard let windowScene = (scene as? UIWindowScene) else { return }
window = UIWindow(windowScene: windowScene)
let rootNavigationController = UIViewController()
window?.rootViewController = rootNavigationController
window?.rootViewController?.view.backgroundColor = .green
window?.makeKeyAndVisible()
}
And it will work for ios 13 , if you want support ios 12 and lower you need also implement this logic in AppDelegate