I have a custom tab bar controller. each tab contains a viewcontroller embedded in a navigation controller. I get a value for pro_user from the database in appledelegate and set it there. then before CustomTabBarController gets launched (in appledelegate), i set it's "pro_user" property to true or false (this works and CustomTabBarController receives the value from appledelegate).
Now i'm trying to pass this same value to the ViewControllers (ViewController1 and ViewController2). each view controller also has a "pro_user" property.I'm doing this by creating the viewcontroller instances and then setting their pro_user property before embedding each viewcontroller in a navigationcontroller. but neither viewcontroller is actually receiving the value of pro_user which i'm setting in CustomTabBarController. I hope this is clear. How do i pass the value of pro_user from CustomTabBarController to each of the view controllers? programmatically (i'm not using storyboards)
class AppDelegate: UIResponder, UIApplicationDelegate {
var pro_user = true
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions:
[UIApplicationLaunchOptionsKey: Any]?) -> Bool {
window = UIWindow(frame:UIScreen.main.bounds)
window?.makeKeyAndVisible()
let customTabBarController = CustomTabBarController()
customTabBarontroller.pro_user = pro_user
self.window?.rootViewController = customTabBarController
return true
}
}
class CustomTabBarController:UITabBarController{
var pro_user : Bool?
override func viewDidLoad(){
super.viewDidLoad()
let viewController1 = ViewController1()
viewController1.pro_user = pro_user //doesn't work
let firstNavigationController = UINavigationController(rootViewController: viewController1)
let viewController2 = ViewController2()
viewController2.pro_user = pro_user //doesn't work
let secondNavigationController = UINavigationController(rootViewController:viewController2)
viewControllers=[firstNavigationController,secondNavigationController]
}
It looks like you're setting a global setting. If so you may want to consider using UserDefaults.
E.g. with a nice extension:
extension UserDefaults {
var isProUser: Bool {
get {
return bool(forKey: "isProUser")
}
set {
set(newValue, forKey: "isProUser")
}
}
}
Then anywhere in your app you can set it:
UserDefaults.standard.isProUser = true
And get it:
let isProUser = UserDefaults.standard.isProUser
The value is also saved between launches.
Related
I have a class with properties updated in viewController. I wanted to save the properties when the app goes into background or quit using AppDelegate. I used the following codes but it appears that the properties were not passed to the AppDelegate. Furthermore the applicationWillTerminate codes did not seem to get executed.
// testClass is defined and the properties are updated in viewController, e.g
testClass.status = true // default is false
// I want to save testClass.status when the app goes into background or being terminated using the following:
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var vc = ViewController()
func applicationDidEnterBackground(_ application: UIApplication) {
print(vc.testClass.status) // prints false
//codes to save
}
// save before App is terminated
func applicationWillTerminate(_ application: UIApplication) {
print(vc.testClass.status) // this code did not get executed?
//codes to save
}
}
applicationWillTerminate is called only when a user terminates the app without switching it to background mode.
When the app is active, double press on Home button and terminate the app.
But if you switch the app to the background, and then try to terminate the app, applicationWillTerminate will not be called.
And you are creating an instance of ViewController in AppDelegate
var vc = ViewController()
If you change the testClass property in another ViewController class instance, you won't get that value here. So create a singleton class like this
class TestClass: NSObject {
static let shared = TestClass()
private override init() {
super.init()
}
var status = false
}
Now update the value in any view controller from the singleton class
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
TestClass.shared.status = true
}
}
In AppDelegate save and retrieve the value from UserDefaults
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
TestClass.shared.status = UserDefaults.standard.bool(forKey: "Status")
return true
}
func applicationDidEnterBackground(_ application: UIApplication) {
UserDefaults.standard.set(TestClass.shared.status, forKey: "Status")
}
func applicationWillTerminate(_ application: UIApplication) {
UserDefaults.standard.set(TestClass.shared.status, forKey: "Status")
}
}
Or create a computed property to save the value in UserDefaults whenever it is changed.
class TestClass: NSObject {
static let shared = TestClass()
private override init() {
super.init()
}
var status: Bool {
get {
return UserDefaults.standard.bool(forKey: "Status")
}
set {
UserDefaults.standard.set(newValue, forKey: "Status")
}
}
}
As already mentioned by others you can ignore applicationWillTerminate.
To get notified when the app goes into the background just add an observer in the view controller.
However rather than didEnterBackground I'd recommend to observe willResignActive.
Add the observer in viewDidLoad once
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(forName: UIApplication.willResignActiveNotification, object: nil, queue: nil) { notification in
// save the properties
}
}
Or if you are using multiple view controllers you can add the observer in viewWillAppear and remove it in viewDidDisappear
Side note:
Never create a view controller with the default initializer ViewController() if you are using storyboard. You'll get a brand new instance which is not the storyboard instance.
I've read several of the suggested posts that were to help with this problem but could not find something for this particular issue.
I need to set a property on my controller, the book is saying to do so in the app delegate. In the previous assignment using a navbar, this worked:
func application(_ application: UIApplication, didFinishLaunchingWithOptions
launchOptions: [UIApplicationLaunchOptionsKey : Any]?) -> Bool {
// Override point for customization after application launch.
// Create an ItemStore to hold list of items
let itemStore = ItemStore()
// Access the ItemsViewController and set its item store
let itemsController = window!.rootViewController as! ItemsViewController
itemsController.itemStore = itemStore
return true
}
However, creating a similar program I need to use tab bar but can't get it to work and keep running into the error stated above, on the let editcontroller = tabcontroller. - line
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
// Create an pindatabase
let pinDataBase = PinDatabase()
// Access the pairsViewController and set its database
let tabController = window!.rootViewController as! UITabBarController
// this edit controller line is where I am stuck
let editController = tabController.tabBar as! EditViewController
editController.pinDataBase = pinDataBase
return true
}
The error is:
fatal error: unexpectedly found nil while unwrapping an Optional value
The controller I'm trying to set the property on is not the root controller but the third tab if that helps.
Your issue is your attempt to cast the UITabBar to your EditViewController. You need to access the array of view controllers from the tab bar controller and access the one that is actually the EditViewController.
let editController = tabController.viewControllers[2] as! EditViewController
This will access the 3rd view controller and cast it as needed.
I currently have the application set up with a UINavigationController as the initial view, which has a UITableViewController as its root view controller. The app runs fine up until this point. I have the following code in AppDelegate.swift:
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
let favLibrary = FavLibrary()
let navController = window!.rootViewController as! UINavigationController
let favController = navController.topViewController as! FLViewController
favController.favLibrary = favLibrary
return true
}
I am trying to implement a UITabBarController so that I can switch between two UITableViewControllers at the same level (Favorites and a Library) using the Tab Bar.
I embed each VC in its own Navigation Controller, then I embed the two Navigation controllers into one Tab Bar Controller.
Upon running the application, it crashes with the following error:
Could not cast value of type 'UITabBarController' (0x115f9e430) to 'UINavigationController' (0x115f971d0).
2018-09-27 15:49:43.811377-0700 appName [3675:954448] Could not cast value of type 'UITabBarController' (0x115f9e430) to 'UINavigationController' (0x115f971d0).
How can I correct the code in AppDelegate to retain functionality with the new arrangement of Tab Bar and Navigation Controllers?
If I understand your question correctly, I suppose you should access the tabBarController first, then retrieve the view controllers it contains, which should be a list of navigation controllers. Then you can get your view controller inside the selected navigation controller:
let tabBar = window!.rootViewController as! UITabBarController
let targetTabNav = tabBar.viewControllers![1] as! UINavigationController // change index to what you want
let targetVc = targetTabNav.viewControllers.first!
// Do what you want with the target Vc ...
I am following John Sundell's post to implement a Navigator pattern (https://www.swiftbysundell.com/posts/navigation-in-swift). The basic idea is that, in contrast to Coordinator pattern, each view controller could simply call navigator.navigate(to: .someScreen) without having to know other view controllers.
My question is that, since in order to construct a view controller I need a navigator, to construct a navigator I need a navigation controller, but I want to make the view controller the root of the navigation controller, what's the best way to resolve this circular dependency in a way that respects the best practices of dependency injection?
Below is the idea of Navigator pattern as illustrated by Sundell
Navigator
protocol Navigator {
associatedtype Destination
func navigate(to destination: Destination)
}
class LoginNavigator: Navigator {
enum Destination {
case loginCompleted(user: User)
case signup
}
private weak var navigationController: UINavigationController?
private let viewControllerFactory: LoginViewControllerFactory
init(navigationController: UINavigationController,
viewControllerFactory: LoginViewControllerFactory) {
self.navigationController = navigationController
self.viewControllerFactory = viewControllerFactory
}
func navigate(to destination: Destination) {
let viewController = makeViewController(for: destination)
navigationController?.pushViewController(viewController, animated: true)
}
private func makeViewController(for destination: Destination) -> UIViewController {
switch destination {
case .loginCompleted(let user):
return viewControllerFactory.makeWelcomeViewController(forUser: user)
case .signup:
return viewControllerFactory.makeSignUpViewController()
}
}
}
View Controller
class LoginViewController: UIViewController {
private let navigator: LoginNavigator
init(navigator: LoginNavigator) {
self.navigator = navigator
super.init(nibName: nil, bundle: nil)
}
private func handleLoginButtonTap() {
navigator.navigate(to: .loginCompleted(user: user))
}
private func handleSignUpButtonTap() {
navigator.navigate(to: .signup)
}
}
Now in AppDelegate I want to do something like
let factory = LoginViewControllerFactory()
let loginViewController = factory.makeLoginViewController()
let rootNavigationController = UINavigationController(rootViewController: loginViewController)
window?.rootViewController = rootNavigationController
But I somehow have to pass the rootNavigationController into the factory in order for the loginViewController to be properly constructed right? Because it needs a navigator, which needs the navigation controller. How to do that?
I also was recently trying to implement Sundell's Navigator pattern and ran into this same circular dependency. I had to add some additional behavior to the initial Navigator to handle this odd bootstrap issue. I believe subsequent Navigators in your app can perfectly follow the blog's suggestion.
Here is the new initial Navigator code using JGuo's (the OP) example:
class LoginNavigator: Navigator {
enum Destination {
case loginCompleted(user: User)
case signup
}
private var navigationController: UINavigationController?
// This ^ doesn't need to be weak, as we will instantiate it here.
private let viewControllerFactory: LoginViewControllerFactory
// New:
private let appWindow: UIWindow?
private var isBootstrapped = false
// We will use this ^ to know whether or not to set the root VC
init(appWindow: UIWindow?, // Pass in your app's UIWindow from the AppDelegate
viewControllerFactory: LoginViewControllerFactory) {
self.appWindow = appWindow
self.viewControllerFactory = viewControllerFactory
}
func navigate(to destination: Destination) {
let viewController = makeViewController(for: destination)
// We'll either call bootstrap or push depending on
// if this is the first time we've launched the app, indicated by isBootstrapped
if self.isBootstrapped {
self.pushViewController(viewController)
} else {
bootstrap(rootViewController: viewController)
self.isBootstrapped = true
}
}
private func makeViewController(for destination: Destination) -> UIViewController {
switch destination {
case .loginCompleted(let user):
return viewControllerFactory.makeWelcomeViewController(forUser: user)
case .signup:
return viewControllerFactory.makeSignUpViewController()
}
}
// Add these two new helper functions below:
private func bootstrap(rootViewController: UIViewController) {
self.navigationController = UINavigationController(rootViewController: rootViewController)
self.appWindow?.rootViewController = self.navigationController
}
private func pushViewController(_ viewController: UIViewController) {
// Setup navigation look & feel appropriate to your app design...
navigationController?.setNavigationBarHidden(true, animated: false)
self.navigationController?.pushViewController(viewController, animated: true)
}
}
And inside the AppDelegate now:
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication,
didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
window = UIWindow(frame: UIScreen.main.bounds)
let factory = LoginViewControllerFactory()
let loginViewController = factory.makeLoginViewController()
loginViewController.navigate(to: .signup) // <- Ideally we wouldn't need to signup on app launch always, but this is the basic idea.
window?.makeKeyAndVisible()
return true
}
...
}
Does this solve it? in AppDelegate:
let factory = LoginViewControllerFactory()
let navController = UINavigationController()
let loginNavigator = LoginNavigator(navigationController: navController, viewControllerFactory: factory)
loginNavigator.navigate(to: .signup) // The example doesn't have a .login Destination, but it can easily be added to the factory, so using .signup instead
window?.rootViewController = navController
Instead of having the rootViewController as a property of the LoginViewControllerFactory, I would suggest to pass it as an argument when calling the 'make' functions:
return viewControllerFactory.makeWelcomeViewController(forUser: user, with: rootViewController)
I have created a view controller in didFinishLaunching method of AppDelegate and assigning it to window's root view controller.
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
// Override point for customization after application launch.
window = UIWindow(frame: UIScreen.mainScreen().bounds) // issue with allocating UIWindow
self.viewController = AKSidePanelController()
self.viewController!.centerPanel = UINavigationController(rootViewController: UIStoryboard.centerViewController()!)
window!.rootViewController = self.viewController
window!.makeKeyAndVisible()
return true
}
func shouldAutorotate() -> Bool {
return true
}
func supportedInterfaceOrientations() -> Int {
return UIInterfaceOrientation.Portrait.rawValue | UIInterfaceOrientation.LandscapeLeft.rawValue | UIInterfaceOrientation.LandscapeRight.rawValue
}
for some reasons, auto rotation is not working. i think the problem is because of allocating window in didfinishlaunching. When i try to launch directly from storyboard(by marking isInitialViewController = yes) without adding any code on didFinishLaunching, autorotation works. As you can see, i need to load "viewController" as rootviewcontroller. What i am doing wrong?
I am using Xcode 6.1
The problem is that i am loading View from storyboard as well as initialising view controller in didFinishLaunchingOption in App delegate. the solution is to avoid loading initial View from storyboard.
Set IsinitialViewController to no and load the view controller from appdelegate
This one helps me to fix the issue. Programmatically set the initial view controller using Storyboards
Note that you have to make "Main storyboard file base name" as empty in plist.